Function IsString

tensorflow/python/util/util.cc:81–87

bool WarnedThatSetIsNotSequence = false;

bool IsString(PyObject* o) {
  return PyBytes_Check(o) ||
#if PY_MAJOR_VERSION < 3
         PyString_Check(o) ||
#endif
         PyUnicode_Check(o);
}

// Equivalent to Python's 'o.__class__.__name__'
// Note that '__class__' attribute is set only in new-style classes.