code: def subdivide_with(self, branches, join_function, name='mixed'):
      
      return _subdivide_context(self, branches, join_function, name)
docs: Branches this pretty tensor and uses an explicit join function.
  
      This should be used in a with statement, for example to fork and join with
      a sum:
  
          with pt.subdivide_with(2, tf.add_n) as [a, b]:
            a...
            b...
  
      Args:
        branches: The number of branches.
        join_function: A function to use when rejoining.
        name: A base name for this branch.
      Returns:
        A python context manager to use in a with statement that supplies a
        sequence of tensors with one per branch.
      Raises:
        ValueError: if join_function is None.