code: def called(self):
      return hasattr(self, "treedef_out")
  
imports: import functools
  from typing import Any
  import jax
  import jax.core
  import jax.interpreters.ad
  import jax.interpreters.batching
  import jax.interpreters.mlir
  import jax.tree_util
  from jaxtyping import PyTree
  from .._filters import combine, is_array, is_array_like, partition
  from .._tree import tree_equal
label_desc: Use image node_id 1 for calling the Flatten obj's underlying member method code with example usage: obj.called() and returns: hasattr