prompt: You will be provided with a partial code base and an issue statement explaining a problem to resolve.
  <issue>
  Make test_tube optional
  **Is your feature request related to a problem? Please describe.**
  `test_tube` is only needed when using `TestTubeLogger`, thus it should not be an install requirement like `mlflow`.
  
  </issue>
  <code>
  [start of pytorch_lightning/logging/__init__.py]
  1 from .base import LightningLoggerBase, rank_zero_only
  2 from .test_tube_logger import TestTubeLogger
  3 
  4 try:
  5     from .mlflow_logger import MLFlowLogger
  6 except ModuleNotFoundError:
  7     pass
  8
  [end of pytorch_lightning/logging/__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/pytorch_lightning/logging/__init__.py b/pytorch_lightning/logging/__init__.py
  --- a/pytorch_lightning/logging/__init__.py
  +++ b/pytorch_lightning/logging/__init__.py
  @@ -1,6 +1,9 @@
   from .base import LightningLoggerBase, rank_zero_only
  -from .test_tube_logger import TestTubeLogger
   
  +try:
  +    from .test_tube_logger import TestTubeLogger
  +except ModuleNotFoundError:
  +    pass
   try:
       from .mlflow_logger import MLFlowLogger
   except ModuleNotFoundError:
  
verification_info: {"golden_diff": "diff --git a/pytorch_lightning/logging/__init__.py b/pytorch_lightning/logging/__init__.py\n--- a/pytorch_lightning/logging/__init__.py\n+++ b/pytorch_lightning/logging/__init__.py\n@@ -1,6 +1,9 @@\n from .base import LightningLoggerBase, rank_zero_only\n-from .test_tube_logger import TestTubeLogger\n \n+try:\n+    from .test_tube_logger import TestTubeLogger\n+except ModuleNotFoundError:\n+    pass\n try:\n     from .mlflow_logger import MLFlowLogger\n except ModuleNotFoundError:\n", "issue": "Make test_tube optional\n**Is your feature request related to a problem? Please describe.**\r\n`test_tube` is only needed when using `TestTubeLogger`, thus it should not be an install requirement like `mlflow`.\n", "before_files": [{"content": "from .base import LightningLoggerBase, rank_zero_only\nfrom .test_tube_logger import TestTubeLogger\n\ntry:\n    from .mlflow_logger import MLFlowLogger\nexcept ModuleNotFoundError:\n    pass\n", "path": "pytorch_lightning/logging/__init__.py"}]}