def back_transform(string):
    """Tranform the string, which can contains not allowed printable chars to the 
    string with escape sequences

    Arguments:
        string(string): string to tranformation
    Return:
        string: the string with escape sequences

    """

    i = 0
    while i < len(string):
        c = ord(string[i])
        if 0 <= c <= 32 or c == 35 or c == 92:
            string = string[0:i] + '\\0' + str(c) + string[i+1:]
        i+=1
    return string