def input(feed):
    text = update_text(0)

    if text == "":
        buffer.set_text(text + feed.swapcase())
    elif text[-2:] == ". ":
        buffer.set_text(text + feed.swapcase())
    elif text[-2:] == "? ":
        buffer.set_text(text + feed.swapcase())
    elif text[-2:] == "! ":
        buffer.set_text(text + feed.swapcase())
    else:
        buffer.set_text(text + feed)