def proposal(self, proposer=None, proposal_expiration=None, proposal_review=None):
if not self._propbuffer:<EOL><INDENT>return self.new_proposal(<EOL>self.tx(), proposer, proposal_expiration, proposal_review<EOL>)<EOL><DEDENT>if proposer:<EOL><INDENT>self._propbuffer[<NUM_LIT:0>].set_proposer(proposer)<EOL><DEDENT>if proposal_expiration:<EOL><INDENT>self._propbuffer[<NUM_LIT:0>].set_expiration(proposal_expiration)<EOL><DEDENT>if proposal_review:<EOL><INDENT>self._propbuffer[<NUM_LIT:0>].set_review(proposal_review)<EOL><DEDENT>return self._propbuffer[<NUM_LIT:0>]<EOL>
Return the default proposal buffer

            ... note:: If any parameter is set, the default proposal
               parameters will be changed!