I wonder how to organize one line by checking if the last part of each line in the file ends with a period (.)

def extract_text_from_subtitle(file_name):
    sub_title_contents = []

    file = open(file_name, 'r')
    for line in file:
        line = line.replace('\n', '')
        if len(line) < 3 and line.isnumeric():
            continue
        elif line.count(':') > 2 and line.count('-->') > 0:
            pass
        elif line == '':
            pass
        else:
            sub_title_contents.append(line)
            print(line)
    file.close()
    return sub_title_contents