code: def _validate_format(self, format):
      if format not in self.FORMAT_VALUES:
          raise ValueError(
              "unknown format type %s, must be one of %s"
              % (format, self.FORMAT_VALUES)
          )
  
imports: from __future__ import division, print_function, absolute_import
  import os
  import sys
  from numpy import asarray, real, imag, conj, zeros, ndarray, concatenate, ones, can_cast
  from numpy.compat import asbytes, asstr
  from scipy._lib.six import string_types
  from scipy.sparse import coo_matrix, isspmatrix
label_desc: Use image node_id 8 for calling the MMFile obj's underlying member method code with example usage: obj._validate_format(format) without return types