prompt: We are currently solving the following issue within our repository. Here is the issue text:
  --- BEGIN ISSUE ---
  `Function` which get no input cannot select `volatile`
  In `Function.__call__`, it checks `volatile` of all input variables, and the same value is used. But, `Function` which get not argument such as `Parameter`, always selects `volatile=False`. it may causes conflict of volatility.
  
  https://github.com/pfnet/chainer/blob/master/chainer/function.py#L132
  `Parameter` always returns `False` here.
  
  
  --- 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/parameter.py`
  Content:
  ```
  1 import numpy
  2 
  3 from chainer import function
  4 from chainer.utils import type_check
  5 
  6 
  7 class Parameter(function.Function):
  8 
  9     """Function that outputs its weight array.
  10 
  11     This is a parameterized function that takes no input and returns a variable
  12     holding a shallow copy of the parameter array.
  13 
  14     Args:
  15         array: Initial parameter array.
  16 
  17     """
  18     parameter_names = 'W',
  19     gradient_names = 'gW',
  20 
  21     def __init__(self, array):
  22         self.W = array
  23         self.gW = numpy.empty_like(array)
  24 
  25     def check_type_forward(self, in_types):
  26         type_check.expect(in_types.size() == 0)
  27 
  28     def forward(self, x):
  29         return self.W,
  30 
  31     def backward(self, x, gy):
  32         self.gW += gy[0]
  33         return ()
  34
  ```
  --- 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/parameter.py b/chainer/functions/parameter.py
  --- a/chainer/functions/parameter.py
  +++ b/chainer/functions/parameter.py
  @@ -22,6 +22,13 @@
           self.W = array
           self.gW = numpy.empty_like(array)
   
  +    def __call__(self, volatile=False):
  +        ret = super(Parameter, self).__call__()
  +        if volatile:
  +            ret.unchain_backward()
  +        ret.volatile = volatile
  +        return ret
  +
       def check_type_forward(self, in_types):
           type_check.expect(in_types.size() == 0)
  
verification_info: {"golden_diff": "diff --git a/chainer/functions/parameter.py b/chainer/functions/parameter.py\n--- a/chainer/functions/parameter.py\n+++ b/chainer/functions/parameter.py\n@@ -22,6 +22,13 @@\n         self.W = array\n         self.gW = numpy.empty_like(array)\n \n+    def __call__(self, volatile=False):\n+        ret = super(Parameter, self).__call__()\n+        if volatile:\n+            ret.unchain_backward()\n+        ret.volatile = volatile\n+        return ret\n+\n     def check_type_forward(self, in_types):\n         type_check.expect(in_types.size() == 0)\n", "issue": "`Function` which get no input cannot select `volatile`\nIn `Function.__call__`, it checks `volatile` of all input variables, and the same value is used. But, `Function` which get not argument such as `Parameter`, always selects `volatile=False`. it may causes conflict of volatility.\n\nhttps://github.com/pfnet/chainer/blob/master/chainer/function.py#L132\n`Parameter` always returns `False` here.\n\n", "before_files": [{"content": "import numpy\n\nfrom chainer import function\nfrom chainer.utils import type_check\n\n\nclass Parameter(function.Function):\n\n    \"\"\"Function that outputs its weight array.\n\n    This is a parameterized function that takes no input and returns a variable\n    holding a shallow copy of the parameter array.\n\n    Args:\n        array: Initial parameter array.\n\n    \"\"\"\n    parameter_names = 'W',\n    gradient_names = 'gW',\n\n    def __init__(self, array):\n        self.W = array\n        self.gW = numpy.empty_like(array)\n\n    def check_type_forward(self, in_types):\n        type_check.expect(in_types.size() == 0)\n\n    def forward(self, x):\n        return self.W,\n\n    def backward(self, x, gy):\n        self.gW += gy[0]\n        return ()\n", "path": "chainer/functions/parameter.py"}], "after_files": [{"content": "import numpy\n\nfrom chainer import function\nfrom chainer.utils import type_check\n\n\nclass Parameter(function.Function):\n\n    \"\"\"Function that outputs its weight array.\n\n    This is a parameterized function that takes no input and returns a variable\n    holding a shallow copy of the parameter array.\n\n    Args:\n        array: Initial parameter array.\n\n    \"\"\"\n    parameter_names = 'W',\n    gradient_names = 'gW',\n\n    def __init__(self, array):\n        self.W = array\n        self.gW = numpy.empty_like(array)\n\n    def __call__(self, volatile=False):\n        ret = super(Parameter, self).__call__()\n        if volatile:\n            ret.unchain_backward()\n        ret.volatile = volatile\n        return ret\n\n    def check_type_forward(self, in_types):\n        type_check.expect(in_types.size() == 0)\n\n    def forward(self, x):\n        return self.W,\n\n    def backward(self, x, gy):\n        self.gW += gy[0]\n        return ()\n", "path": "chainer/functions/parameter.py"}]}