syscalls: add typing information

Change-Id: Ibe479360f39dd70d91d2ee9ac64ca86ac6c0d403
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/docs/+/3369304
Tested-by: Mike Frysinger <vapier@chromium.org>
Auto-Submit: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Ram Chandrasekar <rchandrasekar@google.com>
Commit-Queue: Ram Chandrasekar <rchandrasekar@google.com>
diff --git a/constants/errnos.py b/constants/errnos.py
index 781fe77..bb25b75 100755
--- a/constants/errnos.py
+++ b/constants/errnos.py
@@ -13,6 +13,7 @@
 from pathlib import Path
 import subprocess
 import sys
+from typing import Dict, List, Optional, Tuple
 
 import constants
 
@@ -30,7 +31,7 @@
 START_OF_TABLE = '| number |'
 
 
-def find_symbols(target):
+def find_symbols(target: str) -> Dict[str, str]:
     """Find all the symbols using |target|."""
     cc = '%s-clang' % (target,)
     ret = subprocess.run([cc, '-E', '-dD', '-P', '-'],
@@ -49,7 +50,7 @@
     return table
 
 
-def load_table():
+def load_table() -> Tuple[Dict[str, str], Dict[str, List[str]]]:
     """Return a table of all the symbol values (and aliases)."""
     all_tables = {}
     for target in constants.TARGETS:
@@ -72,7 +73,7 @@
     return (baseline, aliases)
 
 
-def sort_table(table):
+def sort_table(table: Dict[str, str]) -> List[Tuple[str, str]]:
     """Return a sorted table."""
     def sorter(element):
         try:
@@ -83,7 +84,8 @@
     return sorted(table.items(), key=sorter)
 
 
-def get_md_table(table, aliases):
+def get_md_table(table: Dict[str, str],
+                 aliases: Dict[str, List[str]]) -> List[str]:
     """Return the table in markdown format."""
     ret = []
     last_num = 0
@@ -106,7 +108,7 @@
     return ret
 
 
-def get_parser():
+def get_parser() -> argparse.ArgumentParser:
     """Return a command line parser."""
     parser = argparse.ArgumentParser(description=__doc__)
     parser.add_argument('-i', '--inplace', action='store_true',
@@ -114,7 +116,7 @@
     return parser
 
 
-def main(argv):
+def main(argv: List[str]) -> Optional[int]:
     """The main func!"""
     parser = get_parser()
     opts = parser.parse_args(argv)