class Regexp::Expression::Sequence

def quantify(token, text, min = nil, max = nil, mode = :greedy)
  offset = -1
  target = expressions[offset]
  while target and target.is_a?(FreeSpace)
    target = expressions[offset -= 1]
  end
  raise ArgumentError.new("No valid target found for '#{text}' " +
                          "quantifier") unless target
  target.quantify(token, text, min, max, mode)
end