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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 get_space_guid(self):
 """ Returns the GUID for the space currently targeted. Can be set by environment variable with PREDIX_SPACE_GUID. Can be determined by ~/.cf/config.json. """

        if 'PREDIX_SPACE_GUID' in os.environ:
            return os.environ['PREDIX_SPACE_GUID']
        else:
            info = self._get_space_info()
            for key in ('Guid', 'GUID'):
                if key in info.keys():
                    return info[key]
            raise ValueError('Unable to determine cf space guid')