code: def entrez(db, acc):
      
      c1 = ['esearch', '-db', db, '-query', acc]
      c2 = ['efetch', '-db', 'BioSample', '-format', 'docsum']
      p1 = Popen(c1, stdout = PIPE, stderr = PIPE)
      p2 = Popen(c2, stdin = p1.stdout, stdout = PIPE, stderr = PIPE)
      return p2.communicate()
docs: search entrez using specified database
      and accession