prompt: You will be provided with a partial code base and an issue statement explaining a problem to resolve.
  <issue>
  Add type check to Identity Function
  Related to #123
  
  
  </issue>
  <code>
  [start of chainer/functions/identity.py]
  1 from chainer import function
  2 
  3 
  4 class Identity(function.Function):
  5 
  6     """Identity function."""
  7 
  8     def forward(self, xs):
  9         return xs
  10 
  11     def backward(self, xs, gys):
  12         return gys
  13 
  14 
  15 def identity(*inputs):
  16     """Just returns input variables."""
  17     return Identity()(*inputs)
  18
  [end of chainer/functions/identity.py]
  </code>
  
  I need you to solve this issue by generating a single patch file that I can apply directly to this repository using git apply. Please respond with a single patch file in the following format.
  <patch>
  diff --git a/file.py b/file.py
  --- a/file.py
  +++ b/file.py
  @@ -1,27 +1,35 @@
   def euclidean(a, b):
  -    while b:
  -        a, b = b, a % b
  -    return a
  +    if b == 0:
  +        return a
  +    return euclidean(b, a % b)
   
   
   def bresenham(x0, y0, x1, y1):
       points = []
       dx = abs(x1 - x0)
       dy = abs(y1 - y0)
  -    sx = 1 if x0 < x1 else -1
  -    sy = 1 if y0 < y1 else -1
  -    err = dx - dy
  +    x, y = x0, y0
  +    sx = -1 if x0 > x1 else 1
  +    sy = -1 if y0 > y1 else 1
   
  -    while True:
  -        points.append((x0, y0))
  -        if x0 == x1 and y0 == y1:
  -            break
  -        e2 = 2 * err
  -        if e2 > -dy:
  -            err -= dy
  -            x0 += sx
  -        if e2 < dx:
  -            err += dx
  -            y0 += sy
  +    if dx > dy:
  +        err = dx / 2.0
  +        while x != x1:
  +            points.append((x, y))
  +            err -= dy
  +            if err < 0:
  +                y += sy
  +                err += dx
  +            x += sx
  +    else:
  +        err = dy / 2.0
  +        while y != y1:
  +            points.append((x, y))
  +            err -= dx
  +            if err < 0:
  +                x += sx
  +                err += dy
  +            y += sy
  +
  +    points.append((x, y))
       return points
  
  </patch>
golden_diff: diff --git a/chainer/functions/identity.py b/chainer/functions/identity.py
  --- a/chainer/functions/identity.py
  +++ b/chainer/functions/identity.py
  @@ -5,6 +5,9 @@
   
       """Identity function."""
   
  +    def check_type_forward(self, in_types):
  +        pass
  +
       def forward(self, xs):
           return xs
  
verification_info: {"golden_diff": "diff --git a/chainer/functions/identity.py b/chainer/functions/identity.py\n--- a/chainer/functions/identity.py\n+++ b/chainer/functions/identity.py\n@@ -5,6 +5,9 @@\n \n     \"\"\"Identity function.\"\"\"\n \n+    def check_type_forward(self, in_types):\n+        pass\n+\n     def forward(self, xs):\n         return xs\n", "issue": "Add type check to Identity Function\nRelated to #123\n\n", "before_files": [{"content": "from chainer import function\n\n\nclass Identity(function.Function):\n\n    \"\"\"Identity function.\"\"\"\n\n    def forward(self, xs):\n        return xs\n\n    def backward(self, xs, gys):\n        return gys\n\n\ndef identity(*inputs):\n    \"\"\"Just returns input variables.\"\"\"\n    return Identity()(*inputs)\n", "path": "chainer/functions/identity.py"}]}