def parseTopDepth(self, descendants=()):
descendants = list(descendants) orlist(getattr(self.source, '<STR_LIT>', descendants))<EOL>if not descendants:<EOL><INDENT>return -<NUM_LIT:1><EOL><DEDENT>return min(TOC.getHeadingLevel(e, self.hierarchy) for e in descendants)<EOL>
Parse tex for highest tag in hierarchy

        >>> TOC.fromLatex('\\section{Hah}\\subsection{No}').parseTopDepth()
        1
        >>> s = '\\subsubsubsection{Yo}\\subsubsection{Hah}'
        >>> TOC.fromLatex(s).parseTopDepth()
        1
        >>> h = ('section', 'subsubsection', 'subsubsubsection')
        >>> TOC.fromLatex(s, hierarchy=h).parseTopDepth()
        2