parameters: (self)
docstring: Create all needed tensors before applying gradients.
  
      This is called with the name_scope using the "name" that
      users have chosen for the application of gradients.
docstring_summary: Create all needed tensors before applying gradients.
docstring_tokens: Create all needed tensors before applying gradients .
function: def _prepare(self):
      """Create all needed tensors before applying gradients.
  
      This is called with the name_scope using the "name" that
      users have chosen for the application of gradients.
      """
      pass
function_tokens: def _prepare ( self ) : pass