code: def _hertz_to_mel(frequencies_hertz, name=None):
      """Converts frequencies in `frequencies_hertz` in Hertz to the mel scale.
  
      Args:
        frequencies_hertz: A `Tensor` of frequencies in Hertz.
        name: An optional name for the operation.
  
      Returns:
        A `Tensor` of the same shape and type of `frequencies_hertz` containing
        frequencies in the mel scale.
      """
      with ops.name_scope(name, "hertz_to_mel", [frequencies_hertz]):
          frequencies_hertz = ops.convert_to_tensor(frequencies_hertz)
          return _MEL_HIGH_FREQUENCY_Q * math_ops.log(
              1.0 + (frequencies_hertz / _MEL_BREAK_FREQUENCY_HERTZ)
          )
  
file_path: tensorflow/tensorflow/python/ops/signal/mel_ops.py
imports: from tensorflow.python.framework import dtypes
  from tensorflow.python.framework import ops
  from tensorflow.python.framework import tensor
  from tensorflow.python.framework import tensor_util
  from tensorflow.python.ops import array_ops
  from tensorflow.python.ops import math_ops
  from tensorflow.python.ops.signal import shape_ops
  from tensorflow.python.util import dispatch
  from tensorflow.python.util.tf_export import tf_export
label_desc: Use image node_id 2 for calling a global function with example usage: _hertz_to_mel(frequencies_hertz, name) and returns: unknown