prompt: You will be provided with a partial code base and an issue statement explaining a problem to resolve.
  <issue>
  Implement Negation operation for FV HE Scheme
  ## Feature Description
  Negation operations of FV Scheme need to be implemented.
  
  It should Negate a ciphertext object and return the result in ciphertext form.
  
  </issue>
  <code>
  [start of syft/frameworks/torch/he/fv/evaluator.py]
  1 import copy
  2 
  3 from syft.frameworks.torch.he.fv.util.operations import poly_add_mod
  4 from syft.frameworks.torch.he.fv.util.operations import multiply_add_plain_with_delta
  5 from syft.frameworks.torch.he.fv.ciphertext import CipherText
  6 from syft.frameworks.torch.he.fv.plaintext import PlainText
  7 
  8 
  9 class Evaluator:
  10     def __init__(self, context):
  11         self.context = context
  12         self.coeff_modulus = context.param.coeff_modulus
  13         self.plain_modulus = context.param.plain_modulus
  14 
  15     def add(self, op1, op2):
  16         """Adds two operands using FV scheme.
  17 
  18         Args:
  19             op1 (Ciphertext/Plaintext): First argument.
  20             op2 (Ciphertext/Plaintext): Second argument.
  21 
  22         Returns:
  23             If both arguments are Plaintext elements then the result will be a Plaintext object
  24                 otherwise a Ciphertext object with value equivalent to the result of addition
  25                 operation of two provided arguments.
  26         """
  27         if isinstance(op1, CipherText) and isinstance(op2, CipherText):
  28             return self._add_cipher_cipher(op1, op2)
  29 
  30         elif isinstance(op1, PlainText) and isinstance(op2, PlainText):
  31             return self._add_plain_plain(op1, op2)
  32 
  33         elif isinstance(op1, PlainText) and isinstance(op2, CipherText):
  34             return self._add_plain_cipher(op1, op2)
  35 
  36         elif isinstance(op1, CipherText) and isinstance(op2, PlainText):
  37             return self._add_plain_cipher(op2, op1)
  38 
  39         else:
  40             raise TypeError(f"Addition Operation not supported between {type(op1)} and {type(op2)}")
  41 
  42     def _add_cipher_cipher(self, ct1, ct2):
  43         """Adds two ciphertexts.
  44 
  45         Args:
  46             ct1 (Ciphertext): First argument.
  47             ct2 (Ciphertext): Second argument.
  48 
  49         Returns:
  50             A Ciphertext object with value equivalent to result of addition of two provided
  51                 arguments.
  52         """
  53         ct1, ct2 = copy.deepcopy(ct1.data), copy.deepcopy(ct2.data)
  54         result = ct2 if len(ct2) > len(ct1) else ct1
  55 
  56         for i in range(min(len(ct1), len(ct2))):
  57             for j in range(len(self.coeff_modulus)):
  58                 result[i][j] = poly_add_mod(ct1[i][j], ct2[i][j], self.coeff_modulus[j])
  59 
  60         return CipherText(result)
  61 
  62     def _add_plain_cipher(self, pt, ct):
  63         """Adds a ciphertext and a plaintext.
  64 
  65         Args:
  66             pt (Plaintext): First argument.
  67             ct (Ciphertext): Second argument.
  68         Returns:
  69             A Ciphertext object with value equivalent to result of addition of two provided
  70                 arguments.
  71         """
  72         ct = copy.deepcopy(ct)
  73         return multiply_add_plain_with_delta(ct, pt, self.context)
  74 
  75     def _add_plain_plain(self, pt1, pt2):
  76         """Adds two plaintexts object.
  77 
  78         Args:
  79             pt1 (Plaintext): First argument.
  80             pt2 (Plaintext): Second argument.
  81 
  82         Returns:
  83             A Plaintext object with value equivalent to result of addition of two provided
  84                 arguments.
  85         """
  86         pt1, pt2 = copy.deepcopy(pt1), copy.deepcopy(pt2)
  87         return PlainText(poly_add_mod(pt1.data, pt2.data, self.plain_modulus))
  88
  [end of syft/frameworks/torch/he/fv/evaluator.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/syft/frameworks/torch/he/fv/evaluator.py b/syft/frameworks/torch/he/fv/evaluator.py
  --- a/syft/frameworks/torch/he/fv/evaluator.py
  +++ b/syft/frameworks/torch/he/fv/evaluator.py
  @@ -1,6 +1,7 @@
   import copy
   
   from syft.frameworks.torch.he.fv.util.operations import poly_add_mod
  +from syft.frameworks.torch.he.fv.util.operations import negate_mod
   from syft.frameworks.torch.he.fv.util.operations import multiply_add_plain_with_delta
   from syft.frameworks.torch.he.fv.ciphertext import CipherText
   from syft.frameworks.torch.he.fv.plaintext import PlainText
  @@ -39,6 +40,24 @@
           else:
               raise TypeError(f"Addition Operation not supported between {type(op1)} and {type(op2)}")
   
  +    def negate(self, ct):
  +        """Negate a cipher i.e -(ct_value)
  +
  +        Args:
  +            ct (Ciphertext): Ciphertext to be negated.
  +
  +        Returns:
  +            A Ciphertext object with value equivalent to result of -(ct_value).
  +        """
  +        result = copy.deepcopy(ct.data)
  +
  +        for i in range(len(result)):
  +            for j in range(len(result[i])):
  +                for k in range(len(result[i][j])):
  +                    result[i][j][k] = negate_mod(ct.data[i][j][k], self.coeff_modulus[j])
  +
  +        return CipherText(result)
  +
       def _add_cipher_cipher(self, ct1, ct2):
           """Adds two ciphertexts.
  
verification_info: {"golden_diff": "diff --git a/syft/frameworks/torch/he/fv/evaluator.py b/syft/frameworks/torch/he/fv/evaluator.py\n--- a/syft/frameworks/torch/he/fv/evaluator.py\n+++ b/syft/frameworks/torch/he/fv/evaluator.py\n@@ -1,6 +1,7 @@\n import copy\n \n from syft.frameworks.torch.he.fv.util.operations import poly_add_mod\n+from syft.frameworks.torch.he.fv.util.operations import negate_mod\n from syft.frameworks.torch.he.fv.util.operations import multiply_add_plain_with_delta\n from syft.frameworks.torch.he.fv.ciphertext import CipherText\n from syft.frameworks.torch.he.fv.plaintext import PlainText\n@@ -39,6 +40,24 @@\n         else:\n             raise TypeError(f\"Addition Operation not supported between {type(op1)} and {type(op2)}\")\n \n+    def negate(self, ct):\n+        \"\"\"Negate a cipher i.e -(ct_value)\n+\n+        Args:\n+            ct (Ciphertext): Ciphertext to be negated.\n+\n+        Returns:\n+            A Ciphertext object with value equivalent to result of -(ct_value).\n+        \"\"\"\n+        result = copy.deepcopy(ct.data)\n+\n+        for i in range(len(result)):\n+            for j in range(len(result[i])):\n+                for k in range(len(result[i][j])):\n+                    result[i][j][k] = negate_mod(ct.data[i][j][k], self.coeff_modulus[j])\n+\n+        return CipherText(result)\n+\n     def _add_cipher_cipher(self, ct1, ct2):\n         \"\"\"Adds two ciphertexts.\n", "issue": "Implement Negation operation for FV HE Scheme\n## Feature Description\r\nNegation operations of FV Scheme need to be implemented.\r\n\r\nIt should Negate a ciphertext object and return the result in ciphertext form.\n", "before_files": [{"content": "import copy\n\nfrom syft.frameworks.torch.he.fv.util.operations import poly_add_mod\nfrom syft.frameworks.torch.he.fv.util.operations import multiply_add_plain_with_delta\nfrom syft.frameworks.torch.he.fv.ciphertext import CipherText\nfrom syft.frameworks.torch.he.fv.plaintext import PlainText\n\n\nclass Evaluator:\n    def __init__(self, context):\n        self.context = context\n        self.coeff_modulus = context.param.coeff_modulus\n        self.plain_modulus = context.param.plain_modulus\n\n    def add(self, op1, op2):\n        \"\"\"Adds two operands using FV scheme.\n\n        Args:\n            op1 (Ciphertext/Plaintext): First argument.\n            op2 (Ciphertext/Plaintext): Second argument.\n\n        Returns:\n            If both arguments are Plaintext elements then the result will be a Plaintext object\n                otherwise a Ciphertext object with value equivalent to the result of addition\n                operation of two provided arguments.\n        \"\"\"\n        if isinstance(op1, CipherText) and isinstance(op2, CipherText):\n            return self._add_cipher_cipher(op1, op2)\n\n        elif isinstance(op1, PlainText) and isinstance(op2, PlainText):\n            return self._add_plain_plain(op1, op2)\n\n        elif isinstance(op1, PlainText) and isinstance(op2, CipherText):\n            return self._add_plain_cipher(op1, op2)\n\n        elif isinstance(op1, CipherText) and isinstance(op2, PlainText):\n            return self._add_plain_cipher(op2, op1)\n\n        else:\n            raise TypeError(f\"Addition Operation not supported between {type(op1)} and {type(op2)}\")\n\n    def _add_cipher_cipher(self, ct1, ct2):\n        \"\"\"Adds two ciphertexts.\n\n        Args:\n            ct1 (Ciphertext): First argument.\n            ct2 (Ciphertext): Second argument.\n\n        Returns:\n            A Ciphertext object with value equivalent to result of addition of two provided\n                arguments.\n        \"\"\"\n        ct1, ct2 = copy.deepcopy(ct1.data), copy.deepcopy(ct2.data)\n        result = ct2 if len(ct2) > len(ct1) else ct1\n\n        for i in range(min(len(ct1), len(ct2))):\n            for j in range(len(self.coeff_modulus)):\n                result[i][j] = poly_add_mod(ct1[i][j], ct2[i][j], self.coeff_modulus[j])\n\n        return CipherText(result)\n\n    def _add_plain_cipher(self, pt, ct):\n        \"\"\"Adds a ciphertext and a plaintext.\n\n        Args:\n            pt (Plaintext): First argument.\n            ct (Ciphertext): Second argument.\n        Returns:\n            A Ciphertext object with value equivalent to result of addition of two provided\n                arguments.\n        \"\"\"\n        ct = copy.deepcopy(ct)\n        return multiply_add_plain_with_delta(ct, pt, self.context)\n\n    def _add_plain_plain(self, pt1, pt2):\n        \"\"\"Adds two plaintexts object.\n\n        Args:\n            pt1 (Plaintext): First argument.\n            pt2 (Plaintext): Second argument.\n\n        Returns:\n            A Plaintext object with value equivalent to result of addition of two provided\n                arguments.\n        \"\"\"\n        pt1, pt2 = copy.deepcopy(pt1), copy.deepcopy(pt2)\n        return PlainText(poly_add_mod(pt1.data, pt2.data, self.plain_modulus))\n", "path": "syft/frameworks/torch/he/fv/evaluator.py"}]}