provide a way to generate the inverse of a rule

[kevinbarabash]

const rule = defineRuleString('1 * #a', '#a')
const inverse = rule.inverse()  // equivalent to defineRuleString('#a', '1 * #a')

[aliang8]

Not every rule has an inverse (e.g 0 / 1 or 2 - -3). So we can limit the inverses to only rules on addition and multiplication. One solution would just be to reverse the arguments (assuming that there are only two, e.g #a + 0 -> 0 + #a). Or, since we don't have too many rules right now we can hard code it. But that wouldn't be too ideal considering we would probably want to find inverse of other operations. What do you think?

[kevinbarabash]

It may be simpler to just write the reverse rules we want by hand.