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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 page_should_contain_element(self, locator, loglevel='INFO'):

 """Verifies that current page contains `locator` element.
 
 If this keyword fails, it automatically logs the page source
 using the log level specified with the optional `loglevel` argument.
 Giving `NONE` as level disables logging.
 """

        if not self._is_element_present(locator):
            self.log_source(loglevel)
            raise AssertionError("Page should have contained element '%s' "
                                 "but did not" % locator)
        self._info("Current page contains element '%s'." % locator)