docs: def coerce_tuples(cls, generator):
          """This class method converts a generator of ``(K, V)`` tuples (the
          *tuple protocol*), where ``V`` is not yet of the correct type, to a
          generator where it is of the correct type (using the ``coerceitem``
          class property)
          """
          for k, v in generator:
              yield k, cls.coerce_value(v)