prompt: We are currently solving the following issue within our repository. Here is the issue text:
  --- BEGIN ISSUE ---
  Support basic indexing in Variable class
  Currently `Variable` partially supports `__getitem__`. I need full support of basic indexing.
  - [x] int index #1343 
  - [x] slices #1154
  - [x] new axis #1257 
  - [x] elipsis #1343 
  
  see also: http://docs.scipy.org/doc/numpy/reference/arrays.indexing.html#basic-slicing-and-indexing
  
  
  --- END ISSUE ---
  
  Below are some code segments, each from a relevant file. One or more of these files may contain bugs.
  --- BEGIN FILES ---
  Path: `chainer/functions/array/get_item.py`
  Content:
  ```
  1 import collections
  2 
  3 from chainer import cuda
  4 from chainer import function
  5 from chainer.utils import type_check
  6 from chainer import variable
  7 
  8 
  9 class GetItem(function.Function):
  10 
  11     """Function that slices array and extract elements."""
  12 
  13     def __init__(self, slices):
  14         if not isinstance(slices, collections.Iterable):
  15             slices = tuple([slices])
  16         self.slices = slices
  17 
  18     def check_type_forward(self, in_types):
  19         type_check.expect(in_types.size() == 1)
  20         valid_slice = len(self.slices) - self.slices.count(None)
  21         type_check.expect(in_types[0].ndim == valid_slice)
  22 
  23     def forward(self, xs):
  24         ary = xs[0]
  25         return ary[tuple(self.slices)],
  26 
  27     def backward(self, xs, gys):
  28         xp = cuda.get_array_module(*xs)
  29         gy = gys[0]
  30         gx = xp.zeros_like(xs[0])
  31         gx[tuple(self.slices)] = gy
  32         return gx,
  33 
  34 
  35 def get_item(x, slices):
  36     """Extract elements from array with specified shape, axes and offsets.
  37 
  38     Args:
  39         x (tuple of Variables): Variable to be sliced.
  40         slices (slice or tuple of slices): Slice objects to slice variable.
  41 
  42     Returns:
  43         Variable: :class:`~chainer.Variable` object
  44             which contains sliced array of ``x``.
  45 
  46     """
  47     return GetItem(slices)(x)
  48 
  49 
  50 def install_variable_get_item():
  51     variable.Variable.__getitem__ = get_item
  52
  ```
  --- END FILES ---
  
  Please first localize the bug based on the issue statement, and then generate a patch according to the `git diff` format fenced by three backticks.
  
  Here is an example:
  
  ```diff
  diff --git a/examples/server_async.py b/examples/server_async.py
  --- a/examples/server_async.py
  +++ b/examples/server_async.py
  @@ -313,4 +313,4 @@
   
   
   if __name__ == "__main__":
  -    asyncio.run(run_async_server("."), debug=True)
  +    asyncio.run(run_async_server(), debug=True)
  diff --git a/examples/server_sync.py b/examples/server_sync.py
  --- a/examples/server_sync.py
  +++ b/examples/server_sync.py
  @@ -313,5 +313,5 @@
   
   
   if __name__ == "__main__":
  -    server = run_sync_server(".")
  +    server = run_sync_server()
       server.shutdown()
  
  ```
  
golden_diff: diff --git a/chainer/functions/array/get_item.py b/chainer/functions/array/get_item.py
  --- a/chainer/functions/array/get_item.py
  +++ b/chainer/functions/array/get_item.py
  @@ -1,7 +1,11 @@
   import collections
   
  +import numpy
  +
  +import chainer
   from chainer import cuda
   from chainer import function
  +from chainer import utils
   from chainer.utils import type_check
   from chainer import variable
   
  @@ -13,16 +17,29 @@
       def __init__(self, slices):
           if not isinstance(slices, collections.Iterable):
               slices = tuple([slices])
  +
  +        if chainer.is_debug():
  +            n_ellipses = 0
  +            for s in slices:
  +                if numpy.isscalar(s) or s is None or isinstance(s, slice):
  +                    pass
  +                elif s is Ellipsis:
  +                    n_ellipses += 1
  +                else:
  +                    raise ValueError('Only basic indexing is supported')
  +            if n_ellipses > 1:
  +                raise ValueError('Only one Ellipsis is allowed')
  +
           self.slices = slices
   
       def check_type_forward(self, in_types):
           type_check.expect(in_types.size() == 1)
           valid_slice = len(self.slices) - self.slices.count(None)
  -        type_check.expect(in_types[0].ndim == valid_slice)
  +        type_check.expect(in_types[0].ndim >= valid_slice)
   
       def forward(self, xs):
           ary = xs[0]
  -        return ary[tuple(self.slices)],
  +        return utils.force_array(ary[tuple(self.slices)]),
   
       def backward(self, xs, gys):
           xp = cuda.get_array_module(*xs)
  @@ -37,12 +54,19 @@
   
       Args:
           x (tuple of Variables): Variable to be sliced.
  -        slices (slice or tuple of slices): Slice objects to slice variable.
  +        slices (int, slice, None or Ellipsis or tuple of them): Basic slicing
  +            to slice a variable. It supports ``int``, ``slice``, ``newaxis``
  +            (equivalent to ``None``) and ``Ellipsis``.
   
       Returns:
           Variable: :class:`~chainer.Variable` object
               which contains sliced array of ``x``.
   
  +    .. note::
  +
  +       See NumPy document for details of `indexing
  +       <http://docs.scipy.org/doc/numpy/reference/arrays.indexing.html>`_.
  +
       """
       return GetItem(slices)(x)
  
verification_info: {"golden_diff": "diff --git a/chainer/functions/array/get_item.py b/chainer/functions/array/get_item.py\n--- a/chainer/functions/array/get_item.py\n+++ b/chainer/functions/array/get_item.py\n@@ -1,7 +1,11 @@\n import collections\n \n+import numpy\n+\n+import chainer\n from chainer import cuda\n from chainer import function\n+from chainer import utils\n from chainer.utils import type_check\n from chainer import variable\n \n@@ -13,16 +17,29 @@\n     def __init__(self, slices):\n         if not isinstance(slices, collections.Iterable):\n             slices = tuple([slices])\n+\n+        if chainer.is_debug():\n+            n_ellipses = 0\n+            for s in slices:\n+                if numpy.isscalar(s) or s is None or isinstance(s, slice):\n+                    pass\n+                elif s is Ellipsis:\n+                    n_ellipses += 1\n+                else:\n+                    raise ValueError('Only basic indexing is supported')\n+            if n_ellipses > 1:\n+                raise ValueError('Only one Ellipsis is allowed')\n+\n         self.slices = slices\n \n     def check_type_forward(self, in_types):\n         type_check.expect(in_types.size() == 1)\n         valid_slice = len(self.slices) - self.slices.count(None)\n-        type_check.expect(in_types[0].ndim == valid_slice)\n+        type_check.expect(in_types[0].ndim >= valid_slice)\n \n     def forward(self, xs):\n         ary = xs[0]\n-        return ary[tuple(self.slices)],\n+        return utils.force_array(ary[tuple(self.slices)]),\n \n     def backward(self, xs, gys):\n         xp = cuda.get_array_module(*xs)\n@@ -37,12 +54,19 @@\n \n     Args:\n         x (tuple of Variables): Variable to be sliced.\n-        slices (slice or tuple of slices): Slice objects to slice variable.\n+        slices (int, slice, None or Ellipsis or tuple of them): Basic slicing\n+            to slice a variable. It supports ``int``, ``slice``, ``newaxis``\n+            (equivalent to ``None``) and ``Ellipsis``.\n \n     Returns:\n         Variable: :class:`~chainer.Variable` object\n             which contains sliced array of ``x``.\n \n+    .. note::\n+\n+       See NumPy document for details of `indexing\n+       <http://docs.scipy.org/doc/numpy/reference/arrays.indexing.html>`_.\n+\n     \"\"\"\n     return GetItem(slices)(x)\n", "issue": "Support basic indexing in Variable class\nCurrently `Variable` partially supports `__getitem__`. I need full support of basic indexing.\n- [x] int index #1343 \n- [x] slices #1154\n- [x] new axis #1257 \n- [x] elipsis #1343 \n\nsee also: http://docs.scipy.org/doc/numpy/reference/arrays.indexing.html#basic-slicing-and-indexing\n\n", "before_files": [{"content": "import collections\n\nfrom chainer import cuda\nfrom chainer import function\nfrom chainer.utils import type_check\nfrom chainer import variable\n\n\nclass GetItem(function.Function):\n\n    \"\"\"Function that slices array and extract elements.\"\"\"\n\n    def __init__(self, slices):\n        if not isinstance(slices, collections.Iterable):\n            slices = tuple([slices])\n        self.slices = slices\n\n    def check_type_forward(self, in_types):\n        type_check.expect(in_types.size() == 1)\n        valid_slice = len(self.slices) - self.slices.count(None)\n        type_check.expect(in_types[0].ndim == valid_slice)\n\n    def forward(self, xs):\n        ary = xs[0]\n        return ary[tuple(self.slices)],\n\n    def backward(self, xs, gys):\n        xp = cuda.get_array_module(*xs)\n        gy = gys[0]\n        gx = xp.zeros_like(xs[0])\n        gx[tuple(self.slices)] = gy\n        return gx,\n\n\ndef get_item(x, slices):\n    \"\"\"Extract elements from array with specified shape, axes and offsets.\n\n    Args:\n        x (tuple of Variables): Variable to be sliced.\n        slices (slice or tuple of slices): Slice objects to slice variable.\n\n    Returns:\n        Variable: :class:`~chainer.Variable` object\n            which contains sliced array of ``x``.\n\n    \"\"\"\n    return GetItem(slices)(x)\n\n\ndef install_variable_get_item():\n    variable.Variable.__getitem__ = get_item\n", "path": "chainer/functions/array/get_item.py"}], "after_files": [{"content": "import collections\n\nimport numpy\n\nimport chainer\nfrom chainer import cuda\nfrom chainer import function\nfrom chainer import utils\nfrom chainer.utils import type_check\nfrom chainer import variable\n\n\nclass GetItem(function.Function):\n\n    \"\"\"Function that slices array and extract elements.\"\"\"\n\n    def __init__(self, slices):\n        if not isinstance(slices, collections.Iterable):\n            slices = tuple([slices])\n\n        if chainer.is_debug():\n            n_ellipses = 0\n            for s in slices:\n                if numpy.isscalar(s) or s is None or isinstance(s, slice):\n                    pass\n                elif s is Ellipsis:\n                    n_ellipses += 1\n                else:\n                    raise ValueError('Only basic indexing is supported')\n            if n_ellipses > 1:\n                raise ValueError('Only one Ellipsis is allowed')\n\n        self.slices = slices\n\n    def check_type_forward(self, in_types):\n        type_check.expect(in_types.size() == 1)\n        valid_slice = len(self.slices) - self.slices.count(None)\n        type_check.expect(in_types[0].ndim >= valid_slice)\n\n    def forward(self, xs):\n        ary = xs[0]\n        return utils.force_array(ary[tuple(self.slices)]),\n\n    def backward(self, xs, gys):\n        xp = cuda.get_array_module(*xs)\n        gy = gys[0]\n        gx = xp.zeros_like(xs[0])\n        gx[tuple(self.slices)] = gy\n        return gx,\n\n\ndef get_item(x, slices):\n    \"\"\"Extract elements from array with specified shape, axes and offsets.\n\n    Args:\n        x (tuple of Variables): Variable to be sliced.\n        slices (int, slice, None or Ellipsis or tuple of them): Basic slicing\n            to slice a variable. It supports ``int``, ``slice``, ``newaxis``\n            (equivalent to ``None``) and ``Ellipsis``.\n\n    Returns:\n        Variable: :class:`~chainer.Variable` object\n            which contains sliced array of ``x``.\n\n    .. note::\n\n       See NumPy document for details of `indexing\n       <http://docs.scipy.org/doc/numpy/reference/arrays.indexing.html>`_.\n\n    \"\"\"\n    return GetItem(slices)(x)\n\n\ndef install_variable_get_item():\n    variable.Variable.__getitem__ = get_item\n", "path": "chainer/functions/array/get_item.py"}]}