code: def to_versions(self):
          
          versions = []
          for bound in self.bounds:
              if bound.lower.inclusive and bound.upper.inclusive \
                      and (bound.lower.version == bound.upper.version):
                  versions.append(bound.lower.version)
  
          return versions or None
docs: Returns exact version ranges as Version objects, or None if there
          are no exact version ranges present.