code: def getVariantAnnotationId(self, gaVariant, gaAnnotation):
          
          md5 = self.hashVariantAnnotation(gaVariant, gaAnnotation)
          compoundId = datamodel.VariantAnnotationCompoundId(
              self.getCompoundId(), gaVariant.reference_name,
              str(gaVariant.start), md5)
          return str(compoundId)
docs: Produces a stringified compoundId representing a variant
          annotation.
          :param gaVariant:   protocol.Variant
          :param gaAnnotation: protocol.VariantAnnotation
          :return:  compoundId String