code: def find_providers(self, reqt):
          
          matcher = self.get_matcher(reqt)
          name = matcher.key   # case-insensitive
          result = set()
          provided = self.provided
          if name in provided:
              for version, provider in provided[name]:
                  try:
                      match = matcher.match(version)
                  except UnsupportedVersionError:
                      match = False
  
                  if match:
                      result.add(provider)
                      break
          return result
docs: Find the distributions which can fulfill a requirement.
  
          :param reqt: The requirement.
           :type reqt: str
          :return: A set of distribution which can fulfill the requirement.