text: We have in some cases stated that when an excepting proviso is found unconstitutional the substantive provisions which it qualifies cannot stand , for to hold otherwise would be to extend the scope of the law . . . so as to embrace [ situations ] which the legislature passing the statute had , by its very terms , expressly excluded .
  
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  We have said that when a proviso is unconstitutional , the provisions it qualifies can 't stand .