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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 normalize_variables(cls, variables):
 """Make sure version is treated consistently """

        # if the version is False, empty string, etc, throw it out
        if variables.get('version', True) in ('', False, '_NO_VERSION', None):
            del variables['version']
        return super(PackageResource, cls).normalize_variables(variables)