code: def _difference(a, b, aminusb=True, validate_indices=True):
      if not aminusb:
          raise NotImplementedError(
              "Argument `aminusb != True` is currently unimplemented."
          )
      if not validate_indices:
          raise NotImplementedError(
              "Argument `validate_indices != True` is currently unimplemented."
          )
      return np.setdiff1d(a, b)
  
label_desc: Use image node_id 1 for calling a global function with example usage: _difference(a, b, aminusb, validate_indices) and returns: np