code: def _is_known_dtype(dt):
      """Helper returning True if dtype is known."""
      return _is_known_unsigned_by_dtype(
          dt
      ) or _is_known_signed_by_dtype(dt)
  
imports: import functools
  import hashlib
  import numpy
  import tensorflow.compat.v2
  from tensorflow_probability.python.internal import assert_util
  from tensorflow_probability.python.internal import dtype_util
  from tensorflow_probability.python.internal import prefer_static
  from tensorflow_probability.python.internal import reparameterization
  from tensorflow_probability.python.internal import tensorshape_util
  from tensorflow.python.util import tf_inspect
label_desc: Use image node_id 23 for calling a global function with example usage: _is_known_dtype(dt) and returns: unknown