fix(mge/functional): simplify the api of add/remove_axis

GitOrigin-RevId: 2482529704a04dfa7c480142c66395abda2788e1

python_module/megengine/functional/tensor.py

@@ -488,12 +488,12 @@ def transpose(inp: Tensor, pattern: Iterable[int]) -> Tensor:
 
 
 @wrap_io_tensor
-def add_axis(inp: Tensor, axis: Union[int, Iterable[int]]) -> Tensor:
+def add_axis(inp: Tensor, axis: int) -> Tensor:
     r"""
-    Add dimension(s) before given axis/axes
+    Add dimension before given axis.
 
     :param inp: Input tensor
-    :param axis: Place(s) of new axes
+    :param axis: Place of new axes
     :return: The output tensor
 
     Examples:
@@ -504,26 +504,28 @@ def add_axis(inp: Tensor, axis: Union[int, Iterable[int]]) -> Tensor:
         from megengine import tensor
         import megengine.functional as F
         x = tensor([1, 2])
-        out = F.add_axis(x, (0, 2))
+        out = F.add_axis(x, 0)
         print(out.shape)
 
     Outputs:
 
     .. testoutput::
 
-        (1, 2, 1)
+        (1, 2)
 
     """
+    if not isinstance(axis, int):
+        raise ValueError("axis must be int, but got type:{}".format(type(axis)))
     return mgb.opr.add_axis(inp, axis)
 
 
 @wrap_io_tensor
-def remove_axis(inp: Tensor, axis: Union[int, Iterable[int]]) -> Tensor:
+def remove_axis(inp: Tensor, axis: int) -> Tensor:
     r"""
-    Remove dimension(s) of shape 1
+    Remove dimension of shape 1.
 
     :param inp: Input tensor
-    :param axis: Place(s) of axes to be removed
+    :param axis: Place of axis to be removed
     :return: The output tensor
 
     Examples:
@@ -534,16 +536,18 @@ def remove_axis(inp: Tensor, axis: Union[int, Iterable[int]]) -> Tensor:
         from megengine import tensor
         import megengine.functional as F
         x = tensor(np.array([1, 2], dtype=np.int32).reshape(1, 1, 2, 1))
-        out = F.remove_axis(x, (0, 0, 1))
+        out = F.remove_axis(x, 3)
         print(out.shape)
 
     Outputs:
 
     .. testoutput::
 
-        (2,)
+        (1, 1, 2)
 
     """
+    if not isinstance(axis, int):
+        raise ValueError("axis must be int, but got type:{}".format(type(axis)))
     return mgb.opr.remove_axis(inp, axis)