code: def getPysamVariants(self, referenceName, startPosition, endPosition):
          
          if referenceName in self._chromFileMap:
              varFileName = self._chromFileMap[referenceName]
              referenceName, startPosition, endPosition = \
                  self.sanitizeVariantFileFetch(
                      referenceName, startPosition, endPosition)
              cursor = self.getFileHandle(varFileName).fetch(
                  referenceName, startPosition, endPosition)
              for record in cursor:
                  yield record
docs: Returns an iterator over the pysam VCF records corresponding to the
          specified query.