class_docstr: Helper class to create an index of dtypes with incremental values.
code: def get_dtype_index(self, dtype):
      if dtype not in self:
          self[dtype] = len(self) + 1
      return self[dtype]
  
imports: import collections
  import os
  import re
  from packaging import version
  from tensorflow.compiler.tf2tensorrt import _pywrap_py_utils
  from tensorflow.core.protobuf import rewriter_config_pb2
  from tensorflow.python.framework import dtypes
label_desc: Use image node_id 1 for calling the DTypeIndex obj's underlying member method code with example usage: obj.get_dtype_index(dtype) and returns: self