code: def _macs2_cmd(method="chip"):
      
      if method.lower() == "chip":
          cmd = ("{macs2} callpeak -t {chip_bam} -c {input_bam} {paired} "
                  " {genome_size} -n {name} -B {options}")
      elif method.lower() == "atac":
          cmd = ("{macs2} callpeak -t {chip_bam} --nomodel "
                 " {paired} {genome_size} -n {name} -B {options}"
                 " --nolambda --keep-dup all")
      else:
          raise ValueError("chip_method should be chip or atac.")
      return cmd
docs: Main command for macs2 tool.