'********** variable unification 'If something is a bird, then it is a flyer. <<$x --> bird> ==> <$x --> flyer>>. 'If something is a bird, then it is not a flyer. <<$y --> bird> ==> <$y --> flyer>>. %0.00;0.70% 1 'If something is a bird, then usually, it is a flyer. ''outputMustContain('<<$1 --> bird> ==> <$1 --> flyer>>. %0.79;0.92%')