[12] pry(main)> $ Comparable                                                                                                                                                                                                                                                                                                                                                 
Error: Couldn't locate a definition for Comparable!
[16] pry(main)> YARD::Registry.at('Comparable').docstring
=> "The <code>Comparable</code> mixin is used by classes whose objects\nmay be ordered. The class must define the <code><=></code> operator,\nwhich compares the receiver against another object, returning -1, 0,\nor +1 depending on whether the receiver is less than, equal to, or\ngreater than the other object. If the other object is not comparable\nthen the <code><=></code> operator should return nil.\n<code>Comparable</code> uses\n<code><=></code> to implement the conventional comparison operators\n(<code><</code>, <code><=</code>, <code>==</code>, <code>>=</code>,\nand <code>></code>) and the method <code>between?</code>.\n\n   class SizeMatters\n     include Comparable\n     attr :str\n     def <=>(anOther)\n       str.size <=> anOther.str.size\n     end\n     def initialize(str)\n       @str = str\n     end\n     def inspect\n       @str\n     end\n   end\n\n   s1 = SizeMatters.new(\"Z\")\n   s2 = SizeMatters.new(\"YY\")\n   s3 = SizeMatters.new(\"XXX\")\n   s4 = SizeMatters.new(\"WWWW\")\n   s5 = SizeMatters.new(\"VVVVV\")\n\n   s1 < s2                       #=> true\n   s4.between?(s1, s3)           #=> false\n   s4.between?(s3, s5)           #=> true\n   [ s3, s2, s5, s4, s1 ].sort   #=> [Z, YY, XXX, WWWW, VVVVV]"
[17] pry(main)>