#!/usr/bin/python3

filename = 'test3.dat'
file     = open(filename, 'r')

lines = []   # Initialize an empty list

for line in file:
    line = line.rstrip()     # Remove return character
    assert line[0:1] == '!'  # Check the file format
    line = line[1:]          # Remove first character
    lines.append(line)

file.close()

for line in lines:
    print(line)