text: from typing import Callable, List
  
  from pip._internal.req.req_install import InstallRequirement
  from pip._internal.req.req_set import RequirementSet
  
  InstallRequirementProvider = Callable[[str, InstallRequirement], InstallRequirement]
  
  
  class BaseResolver:
      def resolve(self, root_reqs, check_supported_wheels):
          # type: (List[InstallRequirement], bool) -> RequirementSet
          raise NotImplementedError()
  
      def get_installation_order(self, req_set):
          # type: (RequirementSet) -> List[InstallRequirement]
          raise NotImplementedError()
  