code: def rescale(signal, dtype=np.float32):
      """
      Rescale the signal to range [-1, 1] and return as float dtype.
  
      Parameters
      ----------
      signal : numpy array
          Signal to be remixed.
      dtype : numpy dtype
          Data type of the signal.
  
      Returns
      -------
      numpy array
          Signal rescaled to range [-1, 1].
  
      """
      # allow only float dtypes
      if not np.issubdtype(dtype, np.floating):
          raise ValueError(
              "only float dtypes are supported, not %s." % dtype
          )
      # float signals don't need rescaling
      if np.issubdtype(signal.dtype, np.floating):
          return signal.astype(dtype)
      elif np.issubdtype(signal.dtype, np.integer):
          return signal.astype(dtype) / np.iinfo(signal.dtype).max
      else:
          raise ValueError(
              "unsupported signal dtype: %s." % signal.dtype
          )
  
imports: from __future__ import absolute_import, division, print_function
  import warnings
  import numpy
  from ..processors import BufferProcessor, Processor
  from ..utils import integer_types
label_desc: Use image node_id 7 for calling a global function with example usage: rescale(signal, dtype) and returns: signal, unknown