code: def _cached_signature(f):
      if f not in _sig_cache:
          _sig_cache[f] = tf_inspect.signature(f)
      return _sig_cache[f]
  
imports: import contextlib
  import functools
  import threading
  import numpy
  import tensorflow.compat.v2
  from tensorflow.python.framework import composite_tensor
  from tensorflow.python.framework import type_spec
  from tensorflow.python.framework import type_spec_registry
  from tensorflow.python.ops import resource_variable_ops
  from tensorflow.python.util import tf_inspect
  from tensorflow.python.util import variable_utils
label_desc: Use image node_id 4 for calling a global function with example usage: _cached_signature(f) and returns: _sig_cache