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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 open(self, options):
 """ Open and import the refrenced schema. @param options: An options dictionary. @type options: L{options.Options} @return: The referenced schema. @rtype: L{Schema} """

        if self.opened:
            return
        self.opened = True
        log.debug('%s, importing ns="%s", location="%s"',
                  self.id,
                  self.ns[1],
                  self.location
                  )
        result = self.locate()
        if result is None:
            if self.location is None:
                log.debug('imported schema (%s) not-found', self.ns[1])
            else:
                result = self.download(options)
        log.debug('imported:\n%s', result)
        return result