text: from typing import Iterator
  
  from cfp.resolvers.resolver import Resolver
  from cfp.sources import UsePreviousValue
  from cfp.types import ApiParameter
  
  
  class UsePreviousValueResolver(Resolver[UsePreviousValue]):
      def resolve(self) -> Iterator[ApiParameter]:
          """
          Invokes the queued resolution tasks and returns an iterator of the
          values.
          """
  
          for key in self._sources:
              yield ApiParameter(ParameterKey=key, UsePreviousValue=True)
  