new_contents: from subprocess import Popen, PIPE
  
     
  cmd = 'clustalw -align -infile={0} -output=FASTA -outfile=alignement.fa'.format('../data/abcd.fasta')
  clustal_process = Popen(cmd, shell = True, stdout = PIPE, stderr = PIPE)
  stdout, stderr = clustal_process.communicate()
  
  return_code = clustal_process.poll()
  if return_code != 0 :
      raise RuntimeError("something goes wrong with clustalw :"+stderr)
subject: add script for illustrating scripting