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()

```

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'

{"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"}]}