support py3.6 and py3.9

ci/azure-pipelines.yml

@@ -19,11 +19,13 @@ variables:
 jobs:
   - template: job--python-check.yml@templates
     parameters:
-      pythonVersion: "3.8"
+      pythonVersion: "3.9"
 
   - template: job--python-test.yml@templates
     parameters:
       jobs:
+        py36: null
         py37: null
-        py38:
+        py38: null
+        py39:
           coverage: true

scripts/install

@@ -4,7 +4,7 @@ export PREFIX="venv/bin/"
 
 set -x
 
-python -m venv venv
+python3 -m venv venv
 ${PREFIX}python -m pip install -U pip
 ${PREFIX}python -m pip install -r requirements.txt
 

setup.py

@@ -32,8 +32,12 @@ def get_long_description() -> str:
     package_dir={"": "src"},
     include_package_data=True,
     zip_safe=False,
-    install_requires=["anyio~=3.2", "typing-extensions==3.7.*; python_version<'3.8'"],
-    python_requires=">=3.7",
+    install_requires=[
+        "anyio~=3.2",
+        "typing-extensions==3.7.*; python_version<'3.8'",
+        "contextlib2>=21.6.0; python_version<'3.7'",
+    ],
+    python_requires=">=3.6",
     license="MIT",
     classifiers=[
         "Development Status :: 3 - Alpha",
@@ -43,7 +47,9 @@ def get_long_description() -> str:
         "Framework :: Trio",
         "Programming Language :: Python :: 3",
         "Programming Language :: Python :: 3 :: Only",
+        "Programming Language :: Python :: 3.6",
         "Programming Language :: Python :: 3.7",
         "Programming Language :: Python :: 3.8",
+        "Programming Language :: Python :: 3.9",
     ],
 )

src/aiometer/_impl/amap.py

@@ -1,4 +1,4 @@
-from contextlib import asynccontextmanager
+import sys
 from typing import (
     Any,
     AsyncContextManager,
@@ -17,10 +17,15 @@
 from .run_on_each import run_on_each
 from .types import T, U
 
-try:
-    from typing_extensions import Literal  # Python 3.7.
-except ImportError:  # pragma: no cover
-    from typing import Literal  # type: ignore
+if sys.version_info > (3, 8):  # pragma: no cover
+    from typing import Literal
+else:  # pragma: no cover
+    from typing_extensions import Literal
+
+if sys.version_info > (3, 7):  # pragma: no cover
+    from contextlib import asynccontextmanager
+else:  # pragma: no cover
+    from contextlib2 import asynccontextmanager
 
 
 @overload