expand(batch_shape, _instance=None)
  Returns a new distribution instance (or populates an existing
  instance provided by a derived class) with batch dimensions
  expanded to *batch_shape*. This method calls "expand" on the
  distribution's parameters. As such, this does not allocate new
  memory for the expanded distribution instance. Additionally,
  this does not repeat any args checking or parameter broadcasting
  in *__init__.py*, when an instance is first created.

  Parameters:
     * **batch_shape** (*torch.Size*) -- the desired expanded
       size.

     * **_instance** -- new instance provided by subclasses that
       need to override *.expand*.

  Returns:
     New distribution instance with batch dimensions expanded to
     *batch_size*.

icdf(value)
  Returns the inverse cumulative density/mass function evaluated
  at *value*.

  Parameters:
     **value** (*Tensor*) --

  Return type:
     *Tensor*
