parameters: (self, ptn, flag)
docstring: Declare a port on the specified process using the pre-defined trait.
  
          :param ptn: port trait name
          :param flag: required/optional flags
docstring_summary: Declare a port on the specified process using the pre-defined trait.
docstring_tokens: Declare a port on the specified process using the pre - defined trait .
function: def declare_output_port_using_trait(self, ptn, flag):
          """
          Declare a port on the specified process using the pre-defined trait.
  
          :param ptn: port trait name
          :param flag: required/optional flags
  
          """
          port_trait = self._port_trait_set.get(ptn, None)
          if port_trait is None:
              raise ValueError('port trait name \"%s\" not registered' % ptn)
  
          self.declare_output_port(port_trait.name,
                                   port_trait.type_trait.canonical_name,
                                   flag,
                                   port_trait.description)
function_tokens: def declare_output_port_using_trait ( self , ptn , flag ) : port_trait = self . _port_trait_set . get ( ptn , None ) if port_trait is None : raise ValueError ( 'port trait name \"%s\" not registered' % ptn ) self . declare_output_port ( port_trait . name , port_trait . type_trait . canonical_name , flag , port_trait . description )