Add check-toml hook

pre_commit_hooks/check_toml.py

@@ -0,0 +1,28 @@
+from __future__ import print_function
+
+import argparse
+import sys
+from typing import Optional
+from typing import Sequence
+
+import pytoml
+
+
+def main(argv=None):  # type: (Optional[Sequence[str]]) -> int
+    parser = argparse.ArgumentParser()
+    parser.add_argument('filenames', nargs='*', help='Filenames to check.')
+    args = parser.parse_args(argv)
+
+    retval = 0
+    for filename in args.filenames:
+        try:
+            with open(filename) as f:
+                pytoml.load(f)
+        except pytoml.TomlError as exc:
+            print(exc)
+            retval = 1
+    return retval
+
+
+if __name__ == '__main__':
+    sys.exit(main())