Function while_loop_v2

Repeat `body` while the condition `cond` is true. `cond` is a callable returning a boolean scalar tensor. `body` is a callable returning a (possibly nested) tuple, namedtuple or list of tensors of the same arity (length and structure) and types as `loop_vars`. `loop_vars` is a (possibly nes

(cond,
                  body,
                  loop_vars,
                  shape_invariants=None,
                  parallel_iterations=10,
                  back_prop=True,
                  swap_memory=False,
                  maximum_iterations=None,
                  name=None)