Add InvestStatmentLine as possible return from parse_record to fix typing check errors.

src/ofxstatement/parser.py

@@ -4,7 +4,7 @@
 from decimal import Decimal, Decimal as D
 from datetime import datetime
 
-from ofxstatement.statement import Statement, StatementLine
+from ofxstatement.statement import Statement, StatementLine, InvestStatementLine
 
 LT = TypeVar("LT")
 
@@ -53,7 +53,7 @@ def split_records(self) -> Iterable[LT]:  # pragma: no cover
         """Return iterable object consisting of a line per transaction"""
         raise NotImplementedError
 
-    def parse_record(self, line: LT) -> Optional[StatementLine]:  # pragma: no cover
+    def parse_record(self, line: LT) -> Optional[StatementLine|InvestStatementLine]:  # pragma: no cover
         """Parse given transaction line and return StatementLine object"""
         raise NotImplementedError