Remove deprecated --py36 option

README.md

@@ -71,12 +71,6 @@ Options:
                                   Python versions that should be supported by
                                   Black's output. [default: per-file auto-
                                   detection]
-  --py36                          Allow using Python 3.6-only syntax on all
-                                  input files.  This will put trailing commas
-                                  in function signatures and calls also after
-                                  *args and **kwargs. Deprecated; use
-                                  --target-version instead. [default: per-file
-                                  auto-detection]
   --pyi                           Format all input files like typing stubs
                                   regardless of file extension (useful when
                                   piping source on standard input).

black.py

@@ -281,16 +281,6 @@ def target_version_option_callback(
         "per-file auto-detection]"
     ),
 )
-@click.option(
-    "--py36",
-    is_flag=True,
-    help=(
-        "Allow using Python 3.6-only syntax on all input files.  This will put "
-        "trailing commas in function signatures and calls also after *args and "
-        "**kwargs. Deprecated; use --target-version instead. "
-        "[default: per-file auto-detection]"
-    ),
-)
 @click.option(
     "--pyi",
     is_flag=True,
@@ -395,7 +385,6 @@ def main(
     diff: bool,
     fast: bool,
     pyi: bool,
-    py36: bool,
     skip_string_normalization: bool,
     quiet: bool,
     verbose: bool,
@@ -407,17 +396,7 @@ def main(
     """The uncompromising code formatter."""
     write_back = WriteBack.from_configuration(check=check, diff=diff)
     if target_version:
-        if py36:
-            err(f"Cannot use both --target-version and --py36")
-            ctx.exit(2)
-        else:
-            versions = set(target_version)
-    elif py36:
-        err(
-            "--py36 is deprecated and will be removed in a future version. "
-            "Use --target-version py36 instead."
-        )
-        versions = PY36_VERSIONS
+        versions = set(target_version)
     else:
         # We'll autodetect later.
         versions = set()