code: def increment_lineno(node, n=1):
      
      for node in zip((node,), walk(node)):
          if 'lineno' in node._attributes:
              node.lineno = getattr(node, 'lineno', 0) + n
docs: Increment the line numbers of all nodes by `n` if they have line number
      attributes.  This is useful to "move code" to a different location in a
      file.