return NotImplemted for unsupported operations in __array_ufunc__

Author: NoureldinYosri

tunits/core/cython/with_unit_value_array.pyx

@@ -133,7 +133,7 @@ class ValueArray(WithUnit):
         if self._is_dimensionless():
             return getattr(ufunc, method)(*(np.asarray(x) for x in inputs), **kwargs)
 
-        raise NotImplemented
+        return NotImplemented
 
     @property
     def dtype(WithUnit self) -> np.dtype:
@@ -160,4 +160,4 @@ class ValueArray(WithUnit):
     def to_proto(self, msg: Optional['tunits_pb2.ValueArray'] = None) -> 'tunits_pb2.ValueArray':
         ret = _ndarray_to_proto(self.value, msg)
         ret.units.extend(_units_to_proto(self.display_units))
-        return ret
+        return ret