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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 clearPrefix(self, prefix):
 """ Clear the specified prefix from the prefix mappings. @param prefix: A prefix to clear. @type prefix: basestring @return: self @rtype: L{Element} """

        if prefix in self.nsprefixes:
            del self.nsprefixes[prefix]
        return self