code: def _fixed_source_line(self):
          
          line = self.lineno
          _node = self
          try:
              while line is None:
                  _node = next(_node.get_children())
                  line = _node.lineno
          except StopIteration:
              _node = self.parent
              while _node and line is None:
                  line = _node.lineno
                  _node = _node.parent
          return line
docs: Attempt to find the line that this node appears on.
  
          We need this method since not all nodes have :attr:`lineno` set.
  
          :returns: The line number of this node,
              or None if this could not be determined.
          :rtype: int or None