code: def _is_spec(x):
      return x is None or (
          isinstance(x, tuple)
          and all(isinstance(e, str) or e is None for e in x)
      )
  
imports: import functools
  import typing
  import jax
  from jax.experimental import maps
  from jax.sharding import Mesh, PartitionSpec
  from flax.experimental.nnx.nnx import variables
  from flax.experimental.nnx.nnx.pytreelib import TreeNode
  from flax.experimental.nnx.nnx.state import State
label_desc: Use image node_id 8 for calling a global function with example usage: _is_spec(x) and returns: unknown