Code:
def read_all_files():

    global files_and_lines
    
    for files in constants.FILE_NAMES:
        fpath = os.path.join((sys.path[0]),"lexi", files)
        try:
            lexi_file = open(fpath, "r")
            constants.files_and_lines.append(lexi_file.readlines())

        except(IOError):
            print "Something went wrong trying to read the file:"
            print "'%s'" % fpath

        lexi_file.close()