class Regexp::Expression::SequenceOperation

def <<(exp)
  expressions.last << exp
end

def add_sequence
  exp = self.class::OPERAND.new(level, set_level, conditional_level)
  exp.nesting_level = nesting_level + 1
  expressions << exp
  exp
end

def quantify(token, text, min = nil, max = nil, mode = :greedy)
  sequences.last.last.quantify(token, text, min, max, mode)
  sequences.last.last.quantify(token, text, min, max, mode)
end

def starts_at
  expressions.first.starts_at
end

def to_s(format = :full)
  sequences.map { |e| e.to_s(format) }.join(text)
  sequences.map { |e| e.to_s(format) }.join(text)
end