code: def getVariantAnnotations(self, referenceName, startPosition, endPosition):
          
          variantIter = self._variantSet.getPysamVariants(
              referenceName, startPosition, endPosition)
          for record in variantIter:
              yield self.convertVariantAnnotation(record)
docs: Generator for iterating through variant annotations in this
          variant annotation set.
          :param referenceName:
          :param startPosition:
          :param endPosition:
          :return: generator of protocol.VariantAnnotation