code: def program_checks(job, input_args):
      
      # Program checks
      for program in ['curl', 'docker', 'unzip', 'samtools']:
          assert which(program), 'Program "{}" must be installed on every node.'.format(program)
      job.addChildJobFn(download_shared_files, input_args)
docs: Checks that dependency programs are installed.
  
      input_args: dict        Dictionary of input arguments (from main())