class Regexp::Expression::SequenceOperation

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

def add_sequence(active_opts = {})
  self.class::OPERAND.add_to(self, {}, active_opts)
end

def starts_at
  expressions.first.starts_at
end

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