We are currently solving the following issue within our repository. Here is the issue text:
--- BEGIN ISSUE ---
Awkward v2 mixins not propagated upwards
### Version of Awkward Array

2.0.0rc1

### Description and code to reproduce

Coffea tests with awkwardv2 fail with: `E   AttributeError: module 'awkward.behaviors' has no attribute 'mixin_class'`

`awkward.mixin_class` has moved to `awkward.behaviors.mixins.mixin_class`, along with all other mixin decorators.

--- END ISSUE ---

Below are some code segments, each from a relevant file. One or more of these files may contain bugs.
--- BEGIN FILES ---
Path: `src/awkward/__init__.py`
Content:
```
1 # BSD 3-Clause License; see https://github.com/scikit-hep/awkward-1.0/blob/main/LICENSE
2 
3 # NumPy-like alternatives
4 import awkward.nplikes
5 
6 # shims for C++ (now everything is compiled into one 'awkward._ext' module)
7 import awkward._ext
8 
9 # Compiled dynamic modules
10 import awkward._cpu_kernels
11 import awkward._libawkward
12 
13 # layout classes; functionality that used to be in C++ (in Awkward 1.x)
14 import awkward.index
15 import awkward.identifier
16 import awkward.contents
17 import awkward.record
18 import awkward.types
19 import awkward.forms
20 import awkward._slicing
21 import awkward._broadcasting
22 import awkward._typetracer
23 
24 # internal
25 import awkward._util
26 import awkward._errors
27 import awkward._lookup
28 
29 # third-party connectors
30 import awkward._connect.numpy
31 import awkward._connect.numexpr
32 import awkward.numba
33 import awkward.jax
34 
35 # high-level interface
36 from awkward.highlevel import Array
37 from awkward.highlevel import Record
38 from awkward.highlevel import ArrayBuilder
39 
40 # behaviors
41 import awkward.behaviors.categorical
42 import awkward.behaviors.mixins
43 import awkward.behaviors.string
44 
45 behavior = {}
46 awkward.behaviors.string.register(behavior)  # noqa: F405
47 awkward.behaviors.categorical.register(behavior)  # noqa: F405
48 
49 # operations
50 from awkward.operations import *
51 
52 # temporary shim to access v2 under _v2
53 import awkward._v2
54 
55 # version
56 __version__ = awkward._ext.__version__
57 __all__ = [x for x in globals() if not x.startswith("_")]
58 
59 
60 def __dir__():
61     return __all__
62
```
--- 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/src/awkward/__init__.py b/src/awkward/__init__.py
--- a/src/awkward/__init__.py
+++ b/src/awkward/__init__.py
@@ -39,8 +39,8 @@
 
 # behaviors
 import awkward.behaviors.categorical
-import awkward.behaviors.mixins
 import awkward.behaviors.string
+from awkward.behaviors.mixins import mixin_class, mixin_class_method
 
 behavior = {}
 awkward.behaviors.string.register(behavior)  # noqa: F405

{"golden_diff": "diff --git a/src/awkward/__init__.py b/src/awkward/__init__.py\n--- a/src/awkward/__init__.py\n+++ b/src/awkward/__init__.py\n@@ -39,8 +39,8 @@\n \n # behaviors\n import awkward.behaviors.categorical\n-import awkward.behaviors.mixins\n import awkward.behaviors.string\n+from awkward.behaviors.mixins import mixin_class, mixin_class_method\n \n behavior = {}\n awkward.behaviors.string.register(behavior)  # noqa: F405\n", "issue": "Awkward v2 mixins not propagated upwards\n### Version of Awkward Array\r\n\r\n2.0.0rc1\r\n\r\n### Description and code to reproduce\r\n\r\nCoffea tests with awkwardv2 fail with: `E   AttributeError: module 'awkward.behaviors' has no attribute 'mixin_class'`\r\n\r\n`awkward.mixin_class` has moved to `awkward.behaviors.mixins.mixin_class`, along with all other mixin decorators.\n", "before_files": [{"content": "# BSD 3-Clause License; see https://github.com/scikit-hep/awkward-1.0/blob/main/LICENSE\n\n# NumPy-like alternatives\nimport awkward.nplikes\n\n# shims for C++ (now everything is compiled into one 'awkward._ext' module)\nimport awkward._ext\n\n# Compiled dynamic modules\nimport awkward._cpu_kernels\nimport awkward._libawkward\n\n# layout classes; functionality that used to be in C++ (in Awkward 1.x)\nimport awkward.index\nimport awkward.identifier\nimport awkward.contents\nimport awkward.record\nimport awkward.types\nimport awkward.forms\nimport awkward._slicing\nimport awkward._broadcasting\nimport awkward._typetracer\n\n# internal\nimport awkward._util\nimport awkward._errors\nimport awkward._lookup\n\n# third-party connectors\nimport awkward._connect.numpy\nimport awkward._connect.numexpr\nimport awkward.numba\nimport awkward.jax\n\n# high-level interface\nfrom awkward.highlevel import Array\nfrom awkward.highlevel import Record\nfrom awkward.highlevel import ArrayBuilder\n\n# behaviors\nimport awkward.behaviors.categorical\nimport awkward.behaviors.mixins\nimport awkward.behaviors.string\n\nbehavior = {}\nawkward.behaviors.string.register(behavior)  # noqa: F405\nawkward.behaviors.categorical.register(behavior)  # noqa: F405\n\n# operations\nfrom awkward.operations import *\n\n# temporary shim to access v2 under _v2\nimport awkward._v2\n\n# version\n__version__ = awkward._ext.__version__\n__all__ = [x for x in globals() if not x.startswith(\"_\")]\n\n\ndef __dir__():\n    return __all__\n", "path": "src/awkward/__init__.py"}], "after_files": [{"content": "# BSD 3-Clause License; see https://github.com/scikit-hep/awkward-1.0/blob/main/LICENSE\n\n# NumPy-like alternatives\nimport awkward.nplikes\n\n# shims for C++ (now everything is compiled into one 'awkward._ext' module)\nimport awkward._ext\n\n# Compiled dynamic modules\nimport awkward._cpu_kernels\nimport awkward._libawkward\n\n# layout classes; functionality that used to be in C++ (in Awkward 1.x)\nimport awkward.index\nimport awkward.identifier\nimport awkward.contents\nimport awkward.record\nimport awkward.types\nimport awkward.forms\nimport awkward._slicing\nimport awkward._broadcasting\nimport awkward._typetracer\n\n# internal\nimport awkward._util\nimport awkward._errors\nimport awkward._lookup\n\n# third-party connectors\nimport awkward._connect.numpy\nimport awkward._connect.numexpr\nimport awkward.numba\nimport awkward.jax\n\n# high-level interface\nfrom awkward.highlevel import Array\nfrom awkward.highlevel import Record\nfrom awkward.highlevel import ArrayBuilder\n\n# behaviors\nimport awkward.behaviors.categorical\nimport awkward.behaviors.string\nfrom awkward.behaviors.mixins import mixin_class, mixin_class_method\n\nbehavior = {}\nawkward.behaviors.string.register(behavior)  # noqa: F405\nawkward.behaviors.categorical.register(behavior)  # noqa: F405\n\n# operations\nfrom awkward.operations import *\n\n# temporary shim to access v2 under _v2\nimport awkward._v2\n\n# version\n__version__ = awkward._ext.__version__\n__all__ = [x for x in globals() if not x.startswith(\"_\")]\n\n\ndef __dir__():\n    return __all__\n", "path": "src/awkward/__init__.py"}]}