prompt: You will be provided with a partial code base and an issue statement explaining a problem to resolve.
  <issue>
  Create encoding preprocessors not until runtime
  Right now the preprocessors are created at import
  
  https://github.com/pmeier/pystiche/blob/cad5ab6e9485680f2543cf4397d0d21e72a88b9e/pystiche/enc/preprocessing.py#L1-L4
  
  We should only create them if they are needed to speed up the import.
  
  </issue>
  <code>
  [start of pystiche/enc/preprocessing.py]
  1 from torch import nn
  2 from pystiche.image import TorchPreprocessing, CaffePreprocessing
  3 
  4 PREPROCESSORS = {"torch": TorchPreprocessing(), "caffe": CaffePreprocessing()}
  5 
  6 __all__ = ["get_preprocessor"]
  7 
  8 
  9 def get_preprocessor(framework: str) -> nn.Module:
  10     return PREPROCESSORS[framework]
  11
  [end of pystiche/enc/preprocessing.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/pystiche/enc/preprocessing.py b/pystiche/enc/preprocessing.py
  --- a/pystiche/enc/preprocessing.py
  +++ b/pystiche/enc/preprocessing.py
  @@ -1,10 +1,10 @@
   from torch import nn
   from pystiche.image import TorchPreprocessing, CaffePreprocessing
   
  -PREPROCESSORS = {"torch": TorchPreprocessing(), "caffe": CaffePreprocessing()}
  +PREPROCESSORS = {"torch": TorchPreprocessing, "caffe": CaffePreprocessing}
   
   __all__ = ["get_preprocessor"]
   
   
   def get_preprocessor(framework: str) -> nn.Module:
  -    return PREPROCESSORS[framework]
  +    return PREPROCESSORS[framework]()
  
verification_info: {"golden_diff": "diff --git a/pystiche/enc/preprocessing.py b/pystiche/enc/preprocessing.py\n--- a/pystiche/enc/preprocessing.py\n+++ b/pystiche/enc/preprocessing.py\n@@ -1,10 +1,10 @@\n from torch import nn\n from pystiche.image import TorchPreprocessing, CaffePreprocessing\n \n-PREPROCESSORS = {\"torch\": TorchPreprocessing(), \"caffe\": CaffePreprocessing()}\n+PREPROCESSORS = {\"torch\": TorchPreprocessing, \"caffe\": CaffePreprocessing}\n \n __all__ = [\"get_preprocessor\"]\n \n \n def get_preprocessor(framework: str) -> nn.Module:\n-    return PREPROCESSORS[framework]\n+    return PREPROCESSORS[framework]()\n", "issue": "Create encoding preprocessors not until runtime\nRight now the preprocessors are created at import\r\n\r\nhttps://github.com/pmeier/pystiche/blob/cad5ab6e9485680f2543cf4397d0d21e72a88b9e/pystiche/enc/preprocessing.py#L1-L4\r\n\r\nWe should only create them if they are needed to speed up the import.\n", "before_files": [{"content": "from torch import nn\nfrom pystiche.image import TorchPreprocessing, CaffePreprocessing\n\nPREPROCESSORS = {\"torch\": TorchPreprocessing(), \"caffe\": CaffePreprocessing()}\n\n__all__ = [\"get_preprocessor\"]\n\n\ndef get_preprocessor(framework: str) -> nn.Module:\n    return PREPROCESSORS[framework]\n", "path": "pystiche/enc/preprocessing.py"}]}