code: def is_str(x):
      """Returns `True` if :attr:`x` is either a str or unicode. Returns `False`
      otherwise.
      """
      return isinstance(x, six.string_types)
  
file_path: texar/texar/tf/utils/dtypes.py
imports: import six
  import numpy
  import tensorflow
label_desc: Use image node_id 3 for calling a global function with example usage: is_str(x) and returns: isinstance