def guess_contains_png(lines):
    """Tries to determine if a file includes png
    """
    for line in lines:
        if 'libpng error: %s, offset=%d' in line:
            return 1
        if (
            'Application uses deprecated png_write_init() and should be recompiled'
             in line):
            return 1
        if 'libpng version ' in line:
            return 1
    return 0
