code: def _is_known_signed_by_dtype(dt):
      """Helper returning True if dtype is known to be signed."""
      return {
          tf.float16: True,
          tf.float32: True,
          tf.float64: True,
          tf.int8: True,
          tf.int16: True,
          tf.int32: True,
          tf.int64: True,
      }.get(dtype_util.base_dtype(dt), False)
  
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 22 for calling a global function with example usage: _is_known_signed_by_dtype(dt) and returns: dict