modify examples of Cast/NMSWithMask

mindspore/ops/operations/array_ops.py

@@ -174,10 +174,9 @@ class Cast(PrimitiveWithInfer):
     Examples:
         >>> input_np = np.random.randn(2, 3, 4, 5).astype(np.float32)
         >>> input_x = Tensor(input_np)
-        >>> type_dst = mindspore.int32
+        >>> type_dst = mindspore.float16
         >>> cast = P.Cast()
         >>> result = cast(input_x, type_dst)
-        >>> expect = input_np.astype(type_dst)
     """
 
     @prim_attr_register

mindspore/ops/operations/math_ops.py

@@ -1872,7 +1872,7 @@ class NMSWithMask(PrimitiveWithInfer):
         >>> bbox = np.random.rand(128, 5)
         >>> bbox[:, 2] += bbox[:, 0]
         >>> bbox[:, 3] += bbox[:, 1]
-        >>> inputs = Tensor(bbox)
+        >>> inputs = Tensor(bbox, mindspore.float32)
         >>> nms = P.NMSWithMask(0.5)
         >>> output_boxes, indices, mask = nms(inputs)
     """