backup: tweak types for python 3.7 compatibility

backup.py

@@ -29,12 +29,12 @@ def format_size(n: int) -> str:
     return humanfriendly.format_size(n, keep_width=True, binary=True)
 
 class Config:
-    roots: list[bytes]
+    roots: typing.List[bytes]
     max_file_size: typing.Optional[int]
     one_file_system: bool
     exclude_caches: bool
-    exclude: list[bytes]
-    force_include: list[bytes]
+    exclude: typing.List[bytes]
+    force_include: typing.List[bytes]
     notify_email: typing.Optional[str]
 
     def __init__(self, configfile: str):
@@ -93,8 +93,10 @@ class Config:
         self.force_include_re = ([ re.compile(x) for x in a ],
                                  [ re.compile(x) for x in b ])
 
-    def match_re(self, re: tuple[list[typing.Pattern],
-                                 list[typing.Pattern]], path: bytes):
+    def match_re(self,
+                 re: typing.Tuple[typing.List[typing.Pattern],
+                                  typing.List[typing.Pattern]],
+                 path: bytes):
         # Path matches if it matches at least one regex in
         # re[0] and no regex in re[1].
         for a in re[0]:
@@ -109,10 +111,10 @@ class Backup:
     def __init__(self, config: Config, dry_run: bool):
         self.config = config
         self.dry_run = dry_run
-        self.root_seen: dict[bytes, bool] = {}
+        self.root_seen: typing.Dict[bytes, bool] = {}
 
         # Saved log messages
-        self.logs: list[tuple[str, str]] = []
+        self.logs: typing.List[typing.Tuple[str, str]] = []
 
     def out(self, path: bytes):
         self.outfile.write(path + (b'\n' if self.dry_run else b'\0'))
@@ -227,7 +229,7 @@ class Backup:
             self.log('E', f"can't read {pstr(path)}: {str(e)}")
             return
 
-def main(argv: list[str]):
+def main(argv: typing.List[str]):
     import argparse
 
     def humansize(string):
@@ -275,7 +277,7 @@ def main(argv: list[str]):
         backup.log('W', f"failed to parse variables from {args.vars}: {str(e)}")
 
     # Run backup
-    captured_output: list[bytes] = []
+    captured_output: typing.List[bytes] = []
 
     if args.dry_run:
         if args.debug: