The politician labored on deciding which laws should be changed
in the upcoming Act.
would be the same as,
The politician worked on deciding which laws should be changed
in the upcoming Act.
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We haven't labored in vain is the English equivalent of 'Laboravimus non frustra'. In the word by word translation, the verb 'laboravimus' means '[we] have labored, labored'. The adverb 'non 'means 'not'. The adverb 'frustra' means 'vainlessly'.
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They labored, they were exploited and they were killed.