docs: def _only_shifts(self, modifiers):
          """Check if modifiers pressed are only shifts"""
          if not modifiers or len(modifiers) > 2:
              return False
          if len(modifiers) == 2:
              return 'left shift' in modifiers and 'right shift' in modifiers
          if len(modifiers) == 1:
              return 'left shift' in modifiers or 'right shift' in modifiers