Function mixmap

mixmap<T>(aFraction, values): Expression<T>
Returns an expression that creates an interpolated value. This expression is not limited to numbers, but can also be used to interpolate points or colors. For example:
```
  var _ = ExpressionFactory;
  _.mixmap(_.number(0.75), [_.color(orange), _.color(yellow), _.color(red)])
```
results in a color between yellow and red.
Type Parameters
- T extends string | number | Vector3
Parameters
- aFraction: Expression<number>
  The fraction, in range [0,1].
- values: Expression<T>[]
  An array of value expressions.
Returns Expression<T>
An expression that creates an interpolated value.