Fix linting and type errors

1 files changed, 3 insertions, 2 deletions

diff --git a/quality_control/headers.py b/quality_control/headers.py
index 79d7e43..f4f4dad 100644
--- a/quality_control/headers.py
+++ b/quality_control/headers.py
@@ -27,14 +27,15 @@ def invalid_headings(
         enumerate(headings, start=2) if header not in strains)
 
 def duplicate_headings(
-        line_number: int, headers: Sequence[str]) -> Union[InvalidValue, None]:
+        line_number: int,
+        headers: Sequence[str]) -> Tuple[DuplicateHeading, ...]:
     """Return a tuple of `DuplicateHeading` objects for each column heading that
     is a duplicate of another column heading."""
     def __update_columns__(acc, item):
         if item[1] in acc.keys():
             return {**acc, item[1]: acc[item[1]] + (item[0],)}
         return {**acc, item[1]: (item[0],)}
-    repeated = {
+    repeated = {# type: ignore[var-annotated]
         heading: columns for heading, columns in
         reduce(__update_columns__, enumerate(headers, start=1), {}).items()
         if len(columns) > 1