T.boolean

A scalar. Bare form is a fair coin flip.

T.boolean; // 50/50
T.boolean.weighted({ true: 3 }); // 75% true

.weighted({ true, false }) — only one side needs specifying; the other defaults to 1. Weights are relative proportions, not a requirement that they sum to anything in particular. A weight of 0 disables that side (T.boolean.weighted({ true: 0 }) is always false). Every weight zero throws; negative weights, NaN, and Infinity are invalid.