def METHOD_NAME(self, value):
    """Set the placeholder text of the widget.
    GTK.TextView does not have a placeholder option by default so we have to create
    one. We do this by using a separate buffer, and swapping the buffer with the
    "real" buffer whenever focus or content changes.
    """
    self.placeholder.set_text(value)
    self.placeholder.apply_tag(
        self.tag_placeholder,
        self.placeholder.get_start_iter(),
        self.placeholder.get_end_iter(),
    )  # make the placeholder text gray.