prompt: You will be provided with a partial code base and an issue statement explaining a problem to resolve.
  <issue>
  Add an environment variable to skip nltk.download()
  
  Add an environment variable to skip nltk.download()
  
  
  </issue>
  <code>
  [start of deeppavlov/models/__init__.py]
  1 # Copyright 2017 Neural Networks and Deep Learning lab, MIPT
  2 #
  3 # Licensed under the Apache License, Version 2.0 (the "License");
  4 # you may not use this file except in compliance with the License.
  5 # You may obtain a copy of the License at
  6 #
  7 #     http://www.apache.org/licenses/LICENSE-2.0
  8 #
  9 # Unless required by applicable law or agreed to in writing, software
  10 # distributed under the License is distributed on an "AS IS" BASIS,
  11 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  12 # See the License for the specific language governing permissions and
  13 # limitations under the License.
  14 
  15 import nltk
  16 
  17 from deeppavlov.core.common.prints import RedirectedPrints
  18 
  19 
  20 with RedirectedPrints():
  21     nltk.download('punkt')
  22     nltk.download('stopwords')
  23     nltk.download('perluniprops')
  24     nltk.download('nonbreaking_prefixes')
  25
  [end of deeppavlov/models/__init__.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/deeppavlov/models/__init__.py b/deeppavlov/models/__init__.py
  --- a/deeppavlov/models/__init__.py
  +++ b/deeppavlov/models/__init__.py
  @@ -12,13 +12,14 @@
   # See the License for the specific language governing permissions and
   # limitations under the License.
   
  +import os
   import nltk
   
   from deeppavlov.core.common.prints import RedirectedPrints
   
  -
  -with RedirectedPrints():
  -    nltk.download('punkt')
  -    nltk.download('stopwords')
  -    nltk.download('perluniprops')
  -    nltk.download('nonbreaking_prefixes')
  +if not os.environ.get('DP_SKIP_NLTK_DOWNLOAD'):
  +    with RedirectedPrints():
  +        nltk.download('punkt')
  +        nltk.download('stopwords')
  +        nltk.download('perluniprops')
  +        nltk.download('nonbreaking_prefixes')
  
verification_info: {"golden_diff": "diff --git a/deeppavlov/models/__init__.py b/deeppavlov/models/__init__.py\n--- a/deeppavlov/models/__init__.py\n+++ b/deeppavlov/models/__init__.py\n@@ -12,13 +12,14 @@\n # See the License for the specific language governing permissions and\n # limitations under the License.\n \n+import os\n import nltk\n \n from deeppavlov.core.common.prints import RedirectedPrints\n \n-\n-with RedirectedPrints():\n-    nltk.download('punkt')\n-    nltk.download('stopwords')\n-    nltk.download('perluniprops')\n-    nltk.download('nonbreaking_prefixes')\n+if not os.environ.get('DP_SKIP_NLTK_DOWNLOAD'):\n+    with RedirectedPrints():\n+        nltk.download('punkt')\n+        nltk.download('stopwords')\n+        nltk.download('perluniprops')\n+        nltk.download('nonbreaking_prefixes')\n", "issue": "Add an environment variable to skip nltk.download()\n\nAdd an environment variable to skip nltk.download()\n\n", "before_files": [{"content": "# Copyright 2017 Neural Networks and Deep Learning lab, MIPT\n#\n# Licensed under the Apache License, Version 2.0 (the \"License\");\n# you may not use this file except in compliance with the License.\n# You may obtain a copy of the License at\n#\n#     http://www.apache.org/licenses/LICENSE-2.0\n#\n# Unless required by applicable law or agreed to in writing, software\n# distributed under the License is distributed on an \"AS IS\" BASIS,\n# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.\n# See the License for the specific language governing permissions and\n# limitations under the License.\n\nimport nltk\n\nfrom deeppavlov.core.common.prints import RedirectedPrints\n\n\nwith RedirectedPrints():\n    nltk.download('punkt')\n    nltk.download('stopwords')\n    nltk.download('perluniprops')\n    nltk.download('nonbreaking_prefixes')\n", "path": "deeppavlov/models/__init__.py"}]}