code: def iter_transport_opts(opts):
      '''
      Yield transport, opts for all master configured transports
      '''
      transports = set()
  
      for transport, opts_overrides in six.iteritems(opts.get('transport_opts', {})):
          t_opts = dict(opts)
          t_opts.update(opts_overrides)
          t_opts['transport'] = transport
          transports.add(transport)
          yield transport, t_opts
  
      if opts['transport'] not in transports:
          yield opts['transport'], optf iter_transport_opts(opts):
      '''
      Yield transport, opts for all master configured transports
      '''
      transports = set()
  
      for transport, opts_overrides in six.iteritems(opts.get('transport_opts', {})):
          t_opts = dict(opts)
          t_opts.update(opts_overrides)
          t_opts['transport'] = transport
          transports.add(transport)
          yield transport, t_opts
  
      if opts['transport'] not in transports:
          yield opts['transport'], opts
docs: Yield transport, opts for all master configured transports