Take and Drop documentation

6 files changed, 212 insertions, 4 deletions

diff --git a/doc/README.md b/doc/README.md
index fc8e7000..19d261ad 100644
--- a/doc/README.md
+++ b/doc/README.md
@@ -54,6 +54,7 @@ Primitives:
 - [Self-search functions](selfcmp.md) (`⊐⊒∊⍷`)
 - [Shift functions](shift.md) (`»«`)
 - [Solo, Couple, and Merge](couple.md) (`≍>`)
+- [Take and Drop](take.md) (`↑`)
 - [Transpose](transpose.md) (`⍉`)
 - [Windows](windows.md) (`↕`)
 
diff --git a/doc/primitive.md b/doc/primitive.md
index b768be37..1852da20 100644
--- a/doc/primitive.md
+++ b/doc/primitive.md
@@ -39,8 +39,8 @@ Functions that have significant differences from APL functions are marked with a
 | `⥊`   | [Deshape](reshape.md)                               | [Reshape](reshape.md)*
 | `∾`   | [Join](join.md)*                                    | [Join to](join.md)
 | `≍`   | [Solo](couple.md)*                                  | [Couple](couple.md)*
-| `↑`   | [Prefixes](prefixes.md)*                            | [Take](https://aplwiki.com/wiki/Take)
-| `↓`   | [Suffixes](prefixes.md)*                            | [Drop](https://aplwiki.com/wiki/Drop)
+| `↑`   | [Prefixes](prefixes.md)*                            | [Take](take.md)
+| `↓`   | [Suffixes](prefixes.md)*                            | [Drop](take.md)
 | `↕`   | [Range](range.md)                                   | [Windows](windows.md)*
 | `»`   | [Nudge](shift.md)*                                  | [Shift Before](shift.md)*
 | `«`   | [Nudge Back](shift.md)*                             | [Shift After](shift.md)*
diff --git a/doc/take.md b/doc/take.md
index 1cc0b833..8a8d6423 100644
--- a/doc/take.md
+++ b/doc/take.md
@@ -41,3 +41,90 @@ dim ← ⟨2+≠tx,1.96⟩ ⋄ sh ← ¯1.8‿¯0.5
   lg Ge Line wm ≍˜⊸≍ ¯0.3‿1.2+ty
 ⟩
 -->
+
+The basic idea of Take (`↑`) is to get the first few elements of a list, while Drop (`↓`) removes those and returns the rest. Then they are extended in like a billion ways.
+
+- `𝕩` can be an atom, or array of any rank (the result will be an array).
+- `𝕨` can be negative to take or drop from the end instead of the beginning.
+- For Take, if `𝕨` is larger than the length of `𝕩`, then fills are added.
+- `𝕨` can have multiple numbers corresponding to leading axes of `𝕩`.
+- `𝕨` is allowed to be longer than the rank of `𝕩`; `𝕩` will be extended to fit.
+
+These extensions can be combined as well, so there are a lot of possibilities. A good picture to have in mind is cutting out a corner of the array `𝕩`. This is because the result `𝕨↑𝕩` or `𝕨↓𝕩` always aligns with one side of `𝕩` along each axis, so it aligns with the corner where those sides meet.
+
+The result `d↓𝕩` is always the same as `t↑𝕩` for some other argument `t`, but computing `t` wouldn't be too convenient. The reverse isn't true: only Take can insert fills, so results that include them can't come from Drop.
+
+## One axis
+
+Let's start with a natural number `𝕨`. Take gives the first `𝕨` major cells of `𝕩` (or elements of a list), while Drop gives all but the first `𝕨`.
+
+        4 ↑ "take and drop"
+        4 ↓ "take and drop"
+
+        1 ↓ >"maj"‿"orc"‿"ell"
+
+If `𝕨` is too large it's usually not a problem. For Take, fill elements are added to the end to bring `𝕩` up to the required length—although this *will* fail if `𝕩` has no fill element. For Drop, the result is an empty array.
+
+        ↕6
+
+        10 ↑ ↕6
+
+        10 ↓ ↕6
+
+        ≢ 5 ↓ ↕3‿9‿2
+
+If `𝕩` is an atom or unit array, it's converted to a list first. For Take this is useful to make an array of mostly fills; for Drop it's pretty much useless.
+
+        10 ↑ 9
+
+        3 ↓ <"element"
+
+### Negative argument
+
+If `𝕨` is negative then wraps around the other side to take or drop from the end of `𝕩`. It's a lot like negative indices in [Select](select.md) (`⊏`), but while negative indices are asymmetric—`0` is the first entry but `¯1` is the last—this case is symmetric. It's because the place to cut is always *before* the index `𝕨`, cancelling out the negative index asymmetry.
+
+        3 ↑ "abcdeEDCBA"
+
+        ¯3 ↑ "abcdeEDCBA"  # Last three
+
+        ¯3 ↓ "abcdeEDCBA"  # All but the last three
+
+What about `0`? It behaves like it's both positive *and* negative. For Take, the first 0 and last 0 cells are indistinguishable, because they're both empty. For Drop, if you remove 0 cells it doesn't matter whether you start at the front or the back, because you're not going to do anything either way.
+
+        0 ↑ 4‿3‿2  # Nothing
+
+        0 ↓ 4‿3‿2  # Everything
+
+If `|𝕨` is too large, then Take will insert fills at the beginning to keep the result aligned with `𝕩` at the end. Drop returns an empty array as in the positive case. So unlike [Rotate](reverse.md) (`⌽`), which is completely cyclical, Take and Drop work cyclically only around 0.
+
+        ¯6 ↑ "xy"
+
+## Multiple axes
+
+In the general case `𝕨` is a list of integers. They're matched with the leading axes of `𝕩`, so that each affects one axis independently from the others.
+
+        ⊢ m ← (10×↕5) +⌜ ↕7
+
+        ¯4‿2 ↑ m  # Last four rows; first two columns
+
+        ¯4‿2 ↓ m
+
+Now Take and Drop taken together don't include the whole array. Take includes the elements that are selected on *every* axis, while Drop excludes the ones selected on *any* axis. They are opposite corners that meet at some point in the middle of the array (here, at the spot between `2` and `11`).
+
+Any integer values at all can be used, in any combination. Here one axis is shortened and the other's padded with fills. The result of Take has shape `|𝕨`, maybe plus some trailing axes from `𝕩`. Of course, if that's too big for your available memory, your BQN implementation probably can't compute it for you!
+
+        3‿¯12 ↑ m
+
+        ≢ 9‿¯4 ↑ ↕7‿6‿5  # Trailing shape example
+
+If the rank of `𝕩` is *smaller* than the length of `𝕨`, then length-1 axes are added to the beginning until it's equal. Mostly this will be used with Take when `𝕩` is a unit, producing an array that contains `𝕩` and a lot of fills.
+
+        3‿4 ↑ <1‿1
+
+This property also enables a nice little trick with Drop. If `𝕨` is a list of zeros, Drop won't do anything—except extend the rank of `𝕩`. So `(r⥊0)↓a`, or `r ⥊⟜0⊸↓ a`, ensures `a` is an array with rank at least `r` but doesn't change any of the elements. As a special case, `⟨⟩↓v` [Encloses](enclose.md) an atom argument but otherwise has no effect.
+
+        ≢ (3⥊0) ↓ 3
+
+        ≢ (3⥊0) ↓ ↕3
+
+        ≢ (3⥊0) ↓ ↕5‿4‿3‿2
diff --git a/docs/doc/index.html b/docs/doc/index.html
index 99a75305..7ccb5768 100644
--- a/docs/doc/index.html
+++ b/docs/doc/index.html
@@ -60,6 +60,7 @@
 <li><a href="selfcmp.html">Self-search functions</a> (<code><span class='Function'>⊐⊒∊⍷</span></code>)</li>
 <li><a href="shift.html">Shift functions</a> (<code><span class='Function'>»«</span></code>)</li>
 <li><a href="couple.html">Solo, Couple, and Merge</a> (<code><span class='Function'>≍&gt;</span></code>)</li>
+<li><a href="take.html">Take and Drop</a> (<code><span class='Function'>↑</span></code>)</li>
 <li><a href="transpose.html">Transpose</a> (<code><span class='Function'>⍉</span></code>)</li>
 <li><a href="windows.html">Windows</a> (<code><span class='Function'>↕</span></code>)</li>
 </ul>
diff --git a/docs/doc/primitive.html b/docs/doc/primitive.html
index e8eedc23..84bd38b3 100644
--- a/docs/doc/primitive.html
+++ b/docs/doc/primitive.html
@@ -147,12 +147,12 @@
 <tr>
 <td><code><span class='Function'>↑</span></code></td>
 <td><a href="prefixes.html">Prefixes</a>*</td>
-<td><a href="https://aplwiki.com/wiki/Take">Take</a></td>
+<td><a href="take.html">Take</a></td>
 </tr>
 <tr>
 <td><code><span class='Function'>↓</span></code></td>
 <td><a href="prefixes.html">Suffixes</a>*</td>
-<td><a href="https://aplwiki.com/wiki/Drop">Drop</a></td>
+<td><a href="take.html">Drop</a></td>
 </tr>
 <tr>
 <td><code><span class='Function'>↕</span></code></td>
diff --git a/docs/doc/take.html b/docs/doc/take.html
index 78ffafeb..bf54a147 100644
--- a/docs/doc/take.html
+++ b/docs/doc/take.html
@@ -33,3 +33,122 @@
   </g>
 </svg>
 
+<p>The basic idea of Take (<code><span class='Function'>↑</span></code>) is to get the first few elements of a list, while Drop (<code><span class='Function'>↓</span></code>) removes those and returns the rest. Then they are extended in like a billion ways.</p>
+<ul>
+<li><code><span class='Value'>𝕩</span></code> can be an atom, or array of any rank (the result will be an array).</li>
+<li><code><span class='Value'>𝕨</span></code> can be negative to take or drop from the end instead of the beginning.</li>
+<li>For Take, if <code><span class='Value'>𝕨</span></code> is larger than the length of <code><span class='Value'>𝕩</span></code>, then fills are added.</li>
+<li><code><span class='Value'>𝕨</span></code> can have multiple numbers corresponding to leading axes of <code><span class='Value'>𝕩</span></code>.</li>
+<li><code><span class='Value'>𝕨</span></code> is allowed to be longer than the rank of <code><span class='Value'>𝕩</span></code>; <code><span class='Value'>𝕩</span></code> will be extended to fit.</li>
+</ul>
+<p>These extensions can be combined as well, so there are a lot of possibilities. A good picture to have in mind is cutting out a corner of the array <code><span class='Value'>𝕩</span></code>. This is because the result <code><span class='Value'>𝕨</span><span class='Function'>↑</span><span class='Value'>𝕩</span></code> or <code><span class='Value'>𝕨</span><span class='Function'>↓</span><span class='Value'>𝕩</span></code> always aligns with one side of <code><span class='Value'>𝕩</span></code> along each axis, so it aligns with the corner where those sides meet.</p>
+<p>The result <code><span class='Value'>d</span><span class='Function'>↓</span><span class='Value'>𝕩</span></code> is always the same as <code><span class='Value'>t</span><span class='Function'>↑</span><span class='Value'>𝕩</span></code> for some other argument <code><span class='Value'>t</span></code>, but computing <code><span class='Value'>t</span></code> wouldn't be too convenient. The reverse isn't true: only Take can insert fills, so results that include them can't come from Drop.</p>
+<h2 id="one-axis">One axis</h2>
+<p>Let's start with a natural number <code><span class='Value'>𝕨</span></code>. Take gives the first <code><span class='Value'>𝕨</span></code> major cells of <code><span class='Value'>𝕩</span></code> (or elements of a list), while Drop gives all but the first <code><span class='Value'>𝕨</span></code>.</p>
+<a class="replLink" title="Open in the REPL" target="_blank" href="https://mlochbaum.github.io/BQN/try.html#code=NCDihpEgInRha2UgYW5kIGRyb3AiCjQg4oaTICJ0YWtlIGFuZCBkcm9wIgoKMSDihpMgPiJtYWoi4oC/Im9yYyLigL8iZWxsIg==">↗️</a><pre>    <span class='Number'>4</span> <span class='Function'>↑</span> <span class='String'>&quot;take and drop&quot;</span>
+"take"
+    <span class='Number'>4</span> <span class='Function'>↓</span> <span class='String'>&quot;take and drop&quot;</span>
+" and drop"
+
+    <span class='Number'>1</span> <span class='Function'>↓</span> <span class='Function'>&gt;</span><span class='String'>&quot;maj&quot;</span><span class='Ligature'>‿</span><span class='String'>&quot;orc&quot;</span><span class='Ligature'>‿</span><span class='String'>&quot;ell&quot;</span>
+┌─     
+╵"orc  
+  ell" 
+      ┘
+</pre>
+<p>If <code><span class='Value'>𝕨</span></code> is too large it's usually not a problem. For Take, fill elements are added to the end to bring <code><span class='Value'>𝕩</span></code> up to the required length—although this <em>will</em> fail if <code><span class='Value'>𝕩</span></code> has no fill element. For Drop, the result is an empty array.</p>
+<a class="replLink" title="Open in the REPL" target="_blank" href="https://mlochbaum.github.io/BQN/try.html#code=4oaVNgoKMTAg4oaRIOKGlTYKCjEwIOKGkyDihpU2CgriiaIgNSDihpMg4oaVM+KAvznigL8y">↗️</a><pre>    <span class='Function'>↕</span><span class='Number'>6</span>
+⟨ 0 1 2 3 4 5 ⟩
+
+    <span class='Number'>10</span> <span class='Function'>↑</span> <span class='Function'>↕</span><span class='Number'>6</span>
+⟨ 0 1 2 3 4 5 0 0 0 0 ⟩
+
+    <span class='Number'>10</span> <span class='Function'>↓</span> <span class='Function'>↕</span><span class='Number'>6</span>
+⟨⟩
+
+    <span class='Function'>≢</span> <span class='Number'>5</span> <span class='Function'>↓</span> <span class='Function'>↕</span><span class='Number'>3</span><span class='Ligature'>‿</span><span class='Number'>9</span><span class='Ligature'>‿</span><span class='Number'>2</span>
+⟨ 0 9 2 ⟩
+</pre>
+<p>If <code><span class='Value'>𝕩</span></code> is an atom or unit array, it's converted to a list first. For Take this is useful to make an array of mostly fills; for Drop it's pretty much useless.</p>
+<a class="replLink" title="Open in the REPL" target="_blank" href="https://mlochbaum.github.io/BQN/try.html#code=MTAg4oaRIDkKCjMg4oaTIDwiZWxlbWVudCI=">↗️</a><pre>    <span class='Number'>10</span> <span class='Function'>↑</span> <span class='Number'>9</span>
+⟨ 9 0 0 0 0 0 0 0 0 0 ⟩
+
+    <span class='Number'>3</span> <span class='Function'>↓</span> <span class='Function'>&lt;</span><span class='String'>&quot;element&quot;</span>
+⟨⟩
+</pre>
+<h3 id="negative-argument">Negative argument</h3>
+<p>If <code><span class='Value'>𝕨</span></code> is negative then wraps around the other side to take or drop from the end of <code><span class='Value'>𝕩</span></code>. It's a lot like negative indices in <a href="select.html">Select</a> (<code><span class='Function'>⊏</span></code>), but while negative indices are asymmetric—<code><span class='Number'>0</span></code> is the first entry but <code><span class='Number'>¯1</span></code> is the last—this case is symmetric. It's because the place to cut is always <em>before</em> the index <code><span class='Value'>𝕨</span></code>, cancelling out the negative index asymmetry.</p>
+<a class="replLink" title="Open in the REPL" target="_blank" href="https://mlochbaum.github.io/BQN/try.html#code=MyDihpEgImFiY2RlRURDQkEiCgrCrzMg4oaRICJhYmNkZUVEQ0JBIiAgIyBMYXN0IHRocmVlCgrCrzMg4oaTICJhYmNkZUVEQ0JBIiAgIyBBbGwgYnV0IHRoZSBsYXN0IHRocmVl">↗️</a><pre>    <span class='Number'>3</span> <span class='Function'>↑</span> <span class='String'>&quot;abcdeEDCBA&quot;</span>
+"abc"
+
+    <span class='Number'>¯3</span> <span class='Function'>↑</span> <span class='String'>&quot;abcdeEDCBA&quot;</span>  <span class='Comment'># Last three
+</span>"CBA"
+
+    <span class='Number'>¯3</span> <span class='Function'>↓</span> <span class='String'>&quot;abcdeEDCBA&quot;</span>  <span class='Comment'># All but the last three
+</span>"abcdeED"
+</pre>
+<p>What about <code><span class='Number'>0</span></code>? It behaves like it's both positive <em>and</em> negative. For Take, the first 0 and last 0 cells are indistinguishable, because they're both empty. For Drop, if you remove 0 cells it doesn't matter whether you start at the front or the back, because you're not going to do anything either way.</p>
+<a class="replLink" title="Open in the REPL" target="_blank" href="https://mlochbaum.github.io/BQN/try.html#code=MCDihpEgNOKAvzPigL8yICAjIE5vdGhpbmcKCjAg4oaTIDTigL8z4oC/MiAgIyBFdmVyeXRoaW5n">↗️</a><pre>    <span class='Number'>0</span> <span class='Function'>↑</span> <span class='Number'>4</span><span class='Ligature'>‿</span><span class='Number'>3</span><span class='Ligature'>‿</span><span class='Number'>2</span>  <span class='Comment'># Nothing
+</span>⟨⟩
+
+    <span class='Number'>0</span> <span class='Function'>↓</span> <span class='Number'>4</span><span class='Ligature'>‿</span><span class='Number'>3</span><span class='Ligature'>‿</span><span class='Number'>2</span>  <span class='Comment'># Everything
+</span>⟨ 4 3 2 ⟩
+</pre>
+<p>If <code><span class='Function'>|</span><span class='Value'>𝕨</span></code> is too large, then Take will insert fills at the beginning to keep the result aligned with <code><span class='Value'>𝕩</span></code> at the end. Drop returns an empty array as in the positive case. So unlike <a href="reverse.html">Rotate</a> (<code><span class='Function'>⌽</span></code>), which is completely cyclical, Take and Drop work cyclically only around 0.</p>
+<a class="replLink" title="Open in the REPL" target="_blank" href="https://mlochbaum.github.io/BQN/try.html#code=wq82IOKGkSAieHki">↗️</a><pre>    <span class='Number'>¯6</span> <span class='Function'>↑</span> <span class='String'>&quot;xy&quot;</span>
+"    xy"
+</pre>
+<h2 id="multiple-axes">Multiple axes</h2>
+<p>In the general case <code><span class='Value'>𝕨</span></code> is a list of integers. They're matched with the leading axes of <code><span class='Value'>𝕩</span></code>, so that each affects one axis independently from the others.</p>
+<a class="replLink" title="Open in the REPL" target="_blank" href="https://mlochbaum.github.io/BQN/try.html#code=4oqiIG0g4oaQICgxMMOX4oaVNSkgK+KMnCDihpU3CgrCrzTigL8yIOKGkSBtICAjIExhc3QgZm91ciByb3dzOyBmaXJzdCB0d28gY29sdW1ucwoKwq804oC/MiDihpMgbQ==">↗️</a><pre>    <span class='Function'>⊢</span> <span class='Value'>m</span> <span class='Gets'>←</span> <span class='Paren'>(</span><span class='Number'>10</span><span class='Function'>×↕</span><span class='Number'>5</span><span class='Paren'>)</span> <span class='Function'>+</span><span class='Modifier'>⌜</span> <span class='Function'>↕</span><span class='Number'>7</span>
+┌─                      
+╵  0  1  2  3  4  5  6  
+  10 11 12 13 14 15 16  
+  20 21 22 23 24 25 26  
+  30 31 32 33 34 35 36  
+  40 41 42 43 44 45 46  
+                       ┘
+
+    <span class='Number'>¯4</span><span class='Ligature'>‿</span><span class='Number'>2</span> <span class='Function'>↑</span> <span class='Value'>m</span>  <span class='Comment'># Last four rows; first two columns
+</span>┌─       
+╵ 10 11  
+  20 21  
+  30 31  
+  40 41  
+        ┘
+
+    <span class='Number'>¯4</span><span class='Ligature'>‿</span><span class='Number'>2</span> <span class='Function'>↓</span> <span class='Value'>m</span>
+┌─           
+╵ 2 3 4 5 6  
+            ┘
+</pre>
+<p>Now Take and Drop taken together don't include the whole array. Take includes the elements that are selected on <em>every</em> axis, while Drop excludes the ones selected on <em>any</em> axis. They are opposite corners that meet at some point in the middle of the array (here, at the spot between <code><span class='Number'>2</span></code> and <code><span class='Number'>11</span></code>).</p>
+<p>Any integer values at all can be used, in any combination. Here one axis is shortened and the other's padded with fills. The result of Take has shape <code><span class='Function'>|</span><span class='Value'>𝕨</span></code>, maybe plus some trailing axes from <code><span class='Value'>𝕩</span></code>. Of course, if that's too big for your available memory, your BQN implementation probably can't compute it for you!</p>
+<a class="replLink" title="Open in the REPL" target="_blank" href="https://mlochbaum.github.io/BQN/try.html#code=M+KAv8KvMTIg4oaRIG0KCuKJoiA54oC/wq80IOKGkSDihpU34oC/NuKAvzUgICMgVHJhaWxpbmcgc2hhcGUgZXhhbXBsZQ==">↗️</a><pre>    <span class='Number'>3</span><span class='Ligature'>‿</span><span class='Number'>¯12</span> <span class='Function'>↑</span> <span class='Value'>m</span>
+┌─                                
+╵ 0 0 0 0 0  0  1  2  3  4  5  6  
+  0 0 0 0 0 10 11 12 13 14 15 16  
+  0 0 0 0 0 20 21 22 23 24 25 26  
+                                 ┘
+
+    <span class='Function'>≢</span> <span class='Number'>9</span><span class='Ligature'>‿</span><span class='Number'>¯4</span> <span class='Function'>↑</span> <span class='Function'>↕</span><span class='Number'>7</span><span class='Ligature'>‿</span><span class='Number'>6</span><span class='Ligature'>‿</span><span class='Number'>5</span>  <span class='Comment'># Trailing shape example
+</span>⟨ 9 4 5 ⟩
+</pre>
+<p>If the rank of <code><span class='Value'>𝕩</span></code> is <em>smaller</em> than the length of <code><span class='Value'>𝕨</span></code>, then length-1 axes are added to the beginning until it's equal. Mostly this will be used with Take when <code><span class='Value'>𝕩</span></code> is a unit, producing an array that contains <code><span class='Value'>𝕩</span></code> and a lot of fills.</p>
+<a class="replLink" title="Open in the REPL" target="_blank" href="https://mlochbaum.github.io/BQN/try.html#code=M+KAvzQg4oaRIDwx4oC/MQ==">↗️</a><pre>    <span class='Number'>3</span><span class='Ligature'>‿</span><span class='Number'>4</span> <span class='Function'>↑</span> <span class='Function'>&lt;</span><span class='Number'>1</span><span class='Ligature'>‿</span><span class='Number'>1</span>
+┌─                                 
+╵ ⟨ 1 1 ⟩ ⟨ 0 0 ⟩ ⟨ 0 0 ⟩ ⟨ 0 0 ⟩  
+  ⟨ 0 0 ⟩ ⟨ 0 0 ⟩ ⟨ 0 0 ⟩ ⟨ 0 0 ⟩  
+  ⟨ 0 0 ⟩ ⟨ 0 0 ⟩ ⟨ 0 0 ⟩ ⟨ 0 0 ⟩  
+                                  ┘
+</pre>
+<p>This property also enables a nice little trick with Drop. If <code><span class='Value'>𝕨</span></code> is a list of zeros, Drop won't do anything—except extend the rank of <code><span class='Value'>𝕩</span></code>. So <code><span class='Paren'>(</span><span class='Value'>r</span><span class='Function'>⥊</span><span class='Number'>0</span><span class='Paren'>)</span><span class='Function'>↓</span><span class='Value'>a</span></code>, or <code><span class='Value'>r</span> <span class='Function'>⥊</span><span class='Modifier2'>⟜</span><span class='Number'>0</span><span class='Modifier2'>⊸</span><span class='Function'>↓</span> <span class='Value'>a</span></code>, ensures <code><span class='Value'>a</span></code> is an array with rank at least <code><span class='Value'>r</span></code> but doesn't change any of the elements. As a special case, <code><span class='Bracket'>⟨⟩</span><span class='Function'>↓</span><span class='Value'>v</span></code> <a href="enclose.html">Encloses</a> an atom argument but otherwise has no effect.</p>
+<a class="replLink" title="Open in the REPL" target="_blank" href="https://mlochbaum.github.io/BQN/try.html#code=4omiICgz4qWKMCkg4oaTIDMKCuKJoiAoM+KlijApIOKGkyDihpUzCgriiaIgKDPipYowKSDihpMg4oaVNeKAvzTigL8z4oC/Mg==">↗️</a><pre>    <span class='Function'>≢</span> <span class='Paren'>(</span><span class='Number'>3</span><span class='Function'>⥊</span><span class='Number'>0</span><span class='Paren'>)</span> <span class='Function'>↓</span> <span class='Number'>3</span>
+⟨ 1 1 1 ⟩
+
+    <span class='Function'>≢</span> <span class='Paren'>(</span><span class='Number'>3</span><span class='Function'>⥊</span><span class='Number'>0</span><span class='Paren'>)</span> <span class='Function'>↓</span> <span class='Function'>↕</span><span class='Number'>3</span>
+⟨ 1 1 3 ⟩
+
+    <span class='Function'>≢</span> <span class='Paren'>(</span><span class='Number'>3</span><span class='Function'>⥊</span><span class='Number'>0</span><span class='Paren'>)</span> <span class='Function'>↓</span> <span class='Function'>↕</span><span class='Number'>5</span><span class='Ligature'>‿</span><span class='Number'>4</span><span class='Ligature'>‿</span><span class='Number'>3</span><span class='Ligature'>‿</span><span class='Number'>2</span>
+⟨ 5 4 3 2 ⟩
+</pre>