code: def test_reading_mixed_datatypes_fails(self):
      with tempfile.NamedTemporaryFile() as temp:
          _WriteMixedDatatypesExr(temp.name)
          with self.assertRaisesRegexp(
              ValueError, "Channels have mixed datatypes"
          ):
              _, _ = exr.read_exr(temp.name)
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import collections
  import tempfile
  from absl.testing import parameterized
  import Imath
  import numpy
  import OpenEXR
  from six.moves import range
  from tensorflow_graphics.io import exr
  from tensorflow_graphics.util import test_case
label_desc: Use image node_id 2 for calling the ExrTest obj's underlying member method code with example usage: obj.test_reading_mixed_datatypes_fails() without return types