Projections can be proj or wkt strings, or a proj4.Proj object.
Projections can be proj or wkt strings.
Coordinates may be proj4.Point objects, an object of the form `{x:x,y:y}`, or an array of the form `[x,y]`.
Coordinates may an object of the form `{x:x,y:y}` or an array of the form `[x,y]`.
When all 3 arguments are given, the result is that the coordinates are transformed from projection1 to projection 2. And returned in the same format that they were given in.