code: def resolve_policy(identifier):
      if identifier is None:
          return dtype_policy()
      if isinstance(identifier, DTypePolicy):
          return identifier
      if isinstance(identifier, dict):
          return serialization_lib.deserialize_keras_object(identifier)
      if isinstance(identifier, str):
          return DTypePolicy(identifier)
      try:
          return DTypePolicy(backend.standardize_dtype(identifier))
      except:
          raise ValueError(
              "Cannot interpret `dtype` argument. Expected a string "
              f"or an instance of DTypePolicy. Received: dtype={identifier}"
          )
  
imports: from keras import backend
  from keras.mixed_precision.dtype_policy import DTypePolicy
  from keras.mixed_precision.dtype_policy import dtype_policy
  from keras.mixed_precision.dtype_policy import set_dtype_policy
  from keras.saving import serialization_lib
label_desc: Use image node_id 1 for calling a global function with example usage: resolve_policy(identifier) and returns: dtype_policy, identifier, serialization_lib, DTypePolicy, DTypePolicy