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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def parseTopDepth(self, descendants=()):
 """Parse tex for highest tag in hierarchy 1 1 2 """

        descendants = list(descendants) or \
            list(getattr(self.source, 'descendants', descendants))
        if not descendants:
            return -1
        return min(TOC.getHeadingLevel(e, self.hierarchy) for e in descendants)