docs: def snpeff(self):
          """
          Annotation with snpEff 
          """
          # calculate time thread took to finish
          # logging.info('Starting snpEff')
          tstart = datetime.now()
  
          se = snpeff.Snpeff(self.vcf_file)
          std = se.run()
  
          tend = datetime.now()
          execution_time = tend - tstart