code: def merylhistogram(merylfile):
      
      pf, sf = op.splitext(merylfile)
      outfile = pf + ".histogram"
      if need_update(merylfile, outfile):
          cmd = "meryl -Dh -s {0}".format(pf)
          sh(cmd, outfile=outfile)
  
      return outfile
docs: Run meryl to dump histogram to be used in kmer.histogram(). The merylfile
      are the files ending in .mcidx or .mcdat.