def to_header(self) -> str:
        """Convert the header set into an HTTP header string."""
        result = []
        for value, quality in self:
            if quality != 1:
                value = f"{value};q={quality}"
            result.append(value)
        return ",".join(result)
Convert the header set into an HTTP header string.
src/werkzeug/datastructures/accept.py