== String#range

  require 'facets/string/range'

  "a123a567a9".range(/123/).assert == (1..3)
  "a123a567a9".range(/a/).assert == (0..0)

== String#range_all

  "a123a123a9".range_all(/123/).assert == [ (1..3), (5..7) ]
  "a123a567a9".range_all(/a/).assert == [ (0..0), (4..4), (8..8) ]

== String#range_of_line

  a = "0123\n456\n78"
  x = [0..4, 5..8, 9..10]
  r = a.range_of_line
  r.assert == x