code: def substr(input, pos, len, name=None, unit="BYTE"):
      return gen_string_ops.substr(
          input, pos, len, unit=unit, name=name
      )
  
imports: import numpy
  from tensorflow.python.framework import constant_op
  from tensorflow.python.framework import dtypes
  from tensorflow.python.framework import ops
  from tensorflow.python.framework import sparse_tensor
  from tensorflow.python.framework import tensor_util
  from tensorflow.python.ops import array_ops
  from tensorflow.python.ops import gen_parsing_ops
  from tensorflow.python.ops import gen_string_ops
  from tensorflow.python.ops import math_ops
  from tensorflow.python.ops.gen_string_ops import *
  from tensorflow.python.util import compat
  from tensorflow.python.util import deprecation
  from tensorflow.python.util import dispatch
  from tensorflow.python.util.tf_export import tf_export
label_desc: Use image node_id 12 for calling a global function with example usage: substr(input, pos, len, name, unit) and returns: gen_string_ops