def redact_line(line):
    i = 0
    new_line = ''
    while True:
        if len(line) == 13 and line[12].isdigit == True:
            return line
        if i==0:
            if is_phone_num(line[i:i+12]):
                for j in range(i,i+12):
                    if line[j] != '-':
                        new_line += 'X'
                        i+=1
                    else:
                        new_line += line[j]
                        i+=1
            else:
                new_line += line[i]
                i+=1
        elif i == len(line)-12:
            if is_phone_num(line[i:i+12]):
                for j in range(i,i+12):
                    if line[j] != '-':
                        new_line += 'X'
                        i+=1
                    else:
                        new_line += line[j]
                        i+=1
            else:
                new_line += line[i]
                i+=1
        elif i < len(line)-12 and line[i+12].isdigit() == False:
            if is_phone_num(line[i:i+12]):
                for j in range(i,i+12):
                    if line[j] != '-':
                        new_line += 'X'
                        i+=1
                    else:
                        new_line += line[j]
                        i+=1
            else:
                new_line += line[i]
                i+=1
        else:
            new_line += line[i]
            i+=1
        if i == len(line):
            break

    return new_line