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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 fetch(self):
 """Submit the request to the ACS Zeropoints Calculator. This method will: * submit the request * parse the response * format the results into a table with the correct units Returns ------- tab : `astropy.table.QTable` or `None` If the request was successful, returns a table; otherwise, `None`. """

        LOG.info('Checking inputs...')
        valid_inputs = self._check_inputs()

        if valid_inputs:
            LOG.info('Submitting request to {}'.format(self._url))
            self._submit_request()
            if self._failed:
                return

            LOG.info('Parsing the response and formatting the results...')
            self._parse_and_format()
            return self.zpt_table

        LOG.error('Please fix the incorrect input(s)')