def escape(t):
    """HTML-escape the text in `t`."""
    return (t
            # Convert HTML special chars into HTML entities.
            .replace("&", "&amp;").replace("<", "&lt;").replace(">", "&gt;")
            .replace("'", "&#39;").replace('"', "&quot;")
            # Convert runs of spaces: "......" -> "&nbsp;.&nbsp;.&nbsp;."
            .replace("  ", "&nbsp; ")
            # To deal with odd-length runs, convert the final pair of spaces
            # so that "....." -> "&nbsp;.&nbsp;&nbsp;."
            .replace("  ", "&nbsp; ")
        )
HTML-escape the text in `t`.