code: def __iter__(self) -> tp.Iterator[Key]:
      return iter(self._mapping)
  
imports: from __future__ import annotations
  import typing
  import jax
  import jax.tree_util
  from flax import traverse_util
  from flax.experimental.nnx.nnx import filterlib, reprlib
  from flax.experimental.nnx.nnx.variables import Variable
label_desc: Use image node_id 8 for calling the State obj's underlying member method code with example usage: obj.__iter__() and returns: iter