- * enum.chunk { |elt| ... } -> an_enumerator

- * Enumerates over the items, chunking them together based on the return

- * value of the block.

- * Consecutive elements which return the same block value are chunked together.

- * For example, consecutive even numbers and odd numbers can be

- * chunked as follows.

- * [3, 1, 4, 1, 5, 9, 2, 6, 5, 3, 5].chunk { |n|

- * n.even?

- * }.each { |even, ary|

- * p [even, ary]

- * }

- * #=> [false, [3, 1]]

- * # [true, [4]]

- * # [false, [1, 5, 9]]

- * # [true, [2, 6]]

- * # [false, [5, 3, 5]]

- * This method is especially useful for sorted series of elements.

- * The following example counts words for each initial letter.

- * open("/usr/share/dict/words", "r:iso-8859-1") { |f|

- * f.chunk { |line| line.upcase.ord }.each { |ch, lines| p [ch.chr, lines.length] }

- * #=> ["\n", 1]

- * # ["A", 1327]

- * # ["B", 1372]

- * # ["C", 1507]

- * # ["D", 791]

- * # ...

- * The following key values have special meaning:

- * - +nil+ and +:_separator+ specifies that the elements should be dropped.

- * - +:_alone+ specifies that the element should be chunked by itself.

- * Any other symbols that begin with an underscore will raise an error:

- * items.chunk { |item| :_underscore }

- * #=> RuntimeError: symbols beginning with an underscore are reserved

- * +nil+ and +:_separator+ can be used to ignore some elements.

- * +:_alone+ can be used to force items into their own chunk.

- * For example, you can put lines that contain a URL by themselves,

- * and chunk the rest of the lines together, like this:

- *

- * pattern = /http/

- * open(filename) { |f|

- * f.chunk { |line| line =~ pattern ? :_alone : true }.each { |key, lines|

- * pp lines

- * }

- * }

- *

- * If no block is given, an enumerator to `chunk` is returned instead.