Args:
            category: unit category

        Returns: generator over all units of a specific category in this coalition

def get_units_from_category(self, category) -> typing.Iterator['BaseUnit']:
        """
        Args:
            category: unit category

        Returns: generator over all units of a specific category in this coalition
        """
        Mission.validator_group_category.validate(category, 'group category')
        for unit in self.units:

            if unit.group_category == category:
                yield unit