code: def _feed_node(self, value, loc):
          
          node = GenericNode(value, loc)
          if not self.stack:
              yield node
          else:
              top = self.stack[-1]
              if isinstance(top, StackEntryList):
                  top.items.append(node)
              elif isinstance(top, StackEntryComment):
                  self.stack.pop()
              else:
                  assert 0
docs: A helper method called when an S-expression has been recognized.
          Like feed_line, this is a generator that yields newly recognized
          top-level expressions.  If the reader is currently at the top level,
          simply yields the passed expression.  Otherwise, it appends it
          to whatever is currently being parsed and yields nothing.