frequency

Creates a generator that chooses a generator from `pairs` based on the provided likelihoods. The likelihood of a given generator being chosen is its likelihood divided by the sum of all likelihoods. Shrinks toward choosing an earlier generator, as well as shrinking the value generated by the chosen generator. Examples: (gen/sample (gen/frequency [[5 gen/small-integer] [3 (gen/vector gen/small-integer)] [2 gen/boolean]])) => (true [] -1 [0] [1 -4 -4 1] true 4 [] 6 true)