code: def _cnvkit_by_type(items, background):
      
      if len(items + background) == 1:
          return _run_cnvkit_single(items[0])
      elif vcfutils.get_paired_phenotype(items[0]):
          return _run_cnvkit_cancer(items, background)
      else:
          return _run_cnvkit_population(items, background)
docs: Dispatch to specific CNVkit functionality based on input type.