Warn about future python support

cligj/__init__.py

@@ -4,7 +4,7 @@
 ecosystem.
 """
 
-from functools import partial
+import sys
 from warnings import warn
 
 import click
@@ -13,7 +13,9 @@
 
 __version__ = "0.7dev"
 
-# Arguments.
+if sys.version_info < (3, 7):
+    warn("cligj 1.0.0 will require Python >= 3.7", FutureWarning)
+
 
 # Multiple input files.
 files_in_arg = click.argument(

setup.py

@@ -26,6 +26,7 @@
     packages=find_packages(exclude=["ez_setup", "examples", "tests"]),
     include_package_data=True,
     zip_safe=False,
+    python_requires=">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, <4",
     install_requires=["click >= 4.0, < 8"],
     extras_require={"test": ["pytest-cov"],},
 )