We are currently solving the following issue within our repository. Here is the issue text:
--- BEGIN ISSUE ---
module 'netket' has no attribute 'MPI'
With the merge #193 we have lost the MPI module 

--- END ISSUE ---

Below are some code segments, each from a relevant file. One or more of these files may contain bugs.
--- BEGIN FILES ---
Path: `netket/__init__.py`
Content:
```
1 # Copyright 2019 The Simons Foundation, Inc. - All Rights Reserved.
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 from __future__ import absolute_import
16 from . import (
17     _C_netket,
18     dynamics,
19     exact,
20     graph,
21     hilbert,
22     layer,
23     machine,
24     operator,
25     optimizer,
26     output,
27     sampler,
28     stats,
29     supervised,
30     unsupervised,
31     utils,
32     variational,
33 )
34
```
--- 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/netket/__init__.py b/netket/__init__.py
--- a/netket/__init__.py
+++ b/netket/__init__.py
@@ -31,3 +31,4 @@
     utils,
     variational,
 )
+from ._C_netket import MPI, LookupReal, LookupComplex

{"golden_diff": "diff --git a/netket/__init__.py b/netket/__init__.py\n--- a/netket/__init__.py\n+++ b/netket/__init__.py\n@@ -31,3 +31,4 @@\n     utils,\n     variational,\n )\n+from ._C_netket import MPI, LookupReal, LookupComplex\n", "issue": "module 'netket' has no attribute 'MPI'\nWith the merge #193 we have lost the MPI module \n", "before_files": [{"content": "# Copyright 2019 The Simons Foundation, Inc. - All Rights Reserved.\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\nfrom __future__ import absolute_import\nfrom . import (\n    _C_netket,\n    dynamics,\n    exact,\n    graph,\n    hilbert,\n    layer,\n    machine,\n    operator,\n    optimizer,\n    output,\n    sampler,\n    stats,\n    supervised,\n    unsupervised,\n    utils,\n    variational,\n)\n", "path": "netket/__init__.py"}], "after_files": [{"content": "# Copyright 2019 The Simons Foundation, Inc. - All Rights Reserved.\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\nfrom __future__ import absolute_import\nfrom . import (\n    _C_netket,\n    dynamics,\n    exact,\n    graph,\n    hilbert,\n    layer,\n    machine,\n    operator,\n    optimizer,\n    output,\n    sampler,\n    stats,\n    supervised,\n    unsupervised,\n    utils,\n    variational,\n)\nfrom ._C_netket import MPI, LookupReal, LookupComplex\n", "path": "netket/__init__.py"}]}