prompt: We are currently solving the following issue within our repository. Here is the issue text:
  --- BEGIN ISSUE ---
  Replace .step(synchronize=False) with optimizer.skip_synchronize()
  NVIDIA AMP does not support passing additional flags to `optimizer.step()`, such as `optimizer.step(synchronize=False)`.
  
  This PR switches API to use context manager:
  ```python
  optimizer.synchronize()
  with optimizer.skip_synchronize():
      optimizer.step()
  ```
  
  --- END ISSUE ---
  
  Below are some code segments, each from a relevant file. One or more of these files may contain bugs.
  --- BEGIN FILES ---
  Path: `horovod/__init__.py`
  Content:
  ```
  1 __version__ = '0.16.3'
  2
  ```
  --- END FILES ---
  
  Please first localize the bug based on the issue statement, and then generate a patch according to the `git diff` format fenced by three backticks.
  
  Here is an example:
  
  ```diff
  diff --git a/examples/server_async.py b/examples/server_async.py
  --- a/examples/server_async.py
  +++ b/examples/server_async.py
  @@ -313,4 +313,4 @@
   
   
   if __name__ == "__main__":
  -    asyncio.run(run_async_server("."), debug=True)
  +    asyncio.run(run_async_server(), debug=True)
  diff --git a/examples/server_sync.py b/examples/server_sync.py
  --- a/examples/server_sync.py
  +++ b/examples/server_sync.py
  @@ -313,5 +313,5 @@
   
   
   if __name__ == "__main__":
  -    server = run_sync_server(".")
  +    server = run_sync_server()
       server.shutdown()
  
  ```
  
golden_diff: diff --git a/horovod/__init__.py b/horovod/__init__.py
  --- a/horovod/__init__.py
  +++ b/horovod/__init__.py
  @@ -1 +1 @@
  -__version__ = '0.16.3'
  +__version__ = '0.16.4'
  
verification_info: {"golden_diff": "diff --git a/horovod/__init__.py b/horovod/__init__.py\n--- a/horovod/__init__.py\n+++ b/horovod/__init__.py\n@@ -1 +1 @@\n-__version__ = '0.16.3'\n+__version__ = '0.16.4'\n", "issue": "Replace .step(synchronize=False) with optimizer.skip_synchronize()\nNVIDIA AMP does not support passing additional flags to `optimizer.step()`, such as `optimizer.step(synchronize=False)`.\r\n\r\nThis PR switches API to use context manager:\r\n```python\r\noptimizer.synchronize()\r\nwith optimizer.skip_synchronize():\r\n    optimizer.step()\r\n```\n", "before_files": [{"content": "__version__ = '0.16.3'\n", "path": "horovod/__init__.py"}], "after_files": [{"content": "__version__ = '0.16.4'\n", "path": "horovod/__init__.py"}]}