Function union

union<B extends readonly [Lazy<Shape>, ...Lazy<Shape>[]]>(
...branches: B,
): UnionShape<B>
Creates a union shape.

Alternatives are accepted as they are stated: a union that exists proves nothing about the distinguishability of its branches, which is a modelling contract settled when a value is matched. An alternative that is itself a union contributes the alternatives it holds rather than nesting, so that a union of unions reads as the single flat list of alternatives it admits values from.
Type Parameters
- B extends readonly [Lazy<Shape>, ...Lazy<Shape>[]]
  The alternatives a value may be drawn from
Parameters
- ...branches: B
  The shapes a value may be drawn from, each possibly deferred to break definition cycles
Returns UnionShape<B>
An immutable shape admitting the values any of the branches admits
Example
```
const location = optional(union(
    string(),
    reference(PostalAddress)
));
```
- Defined in src/union/index.ts:201