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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def pull(args):
 """ %prog pull libfile Pull the sequences using the first column in the libfile. """

    p = OptionParser(pull.__doc__)
    p.set_db_opts(dbname="mtg2", credentials=None)
    p.add_option("--frag", default=False, action="store_true",
            help="The command to pull sequences from db [default: %default]")
    opts, args = p.parse_args(args)

    if len(args) != 1:
        sys.exit(not p.print_help())

    libfile, = args

    dbname = opts.dbname
    frag = opts.frag
    fp = open(libfile)
    hostname, username, password = get_profile()

    for row in fp:
        lib_id, name = row.split("|", 1)
        sqlfile = lib_id + ".sql"

        if not op.exists(sqlfile):
            fw = open(sqlfile, "w")
            print("select seq_name from sequence where seq_name like" + \
                    " '{0}%' and trash is null".format(lib_id), file=fw)
            fw.close()

        if frag:
            cmd = "pullfrag -D {0} -n {1}.sql -o {1} -q -S {2}".format(dbname, lib_id, hostname)
            cmd += " -U {0} -P {1}".format(username, password)
        else:
            cmd = "pullseq -D {0} -n {1}.sql -o {1} -q".format(dbname, lib_id)
        sh(cmd)