docs: def as_string(self, name=None):
          """
          Declares a stream converting each tuple on this stream
          into a string using `str(tuple)`.
  
          The stream is typed as a :py:const:`string stream <streamsx.topology.schema.CommonSchema.String>`.
  
          If this stream is already typed as a string stream then it will
          be returned (with no additional processing against it and `name`
          is ignored).
  
          Args:
              name(str): Name of the resulting stream.
                  When `None` defaults to a generated name.
  
          .. versionadded:: 1.6
          .. versionadded:: 1.6.1 `name` parameter added.
  
          Returns:
              Stream: Stream containing the string representations of tuples on this stream.
          """
          sas = self._change_schema(streamsx.topology.schema.CommonSchema.String, 'as_string', name)._layout('AsString')
          sas.oport.operator.sl = _SourceLocation(_source_info(), 'as_string')
          return sas