### 12.12.7 The length of a segment in space: distance

See section 11.14.2 for distances in two-dimensional
geometry.

The distance command takes as arguments two points or two
lists with the coordinates of the points.

distance returns the distance between these two points.

Input:

distance(point(-1,1,1),point(1,1,1))

or:

distance([-1,1,1],[1,1,1])

Output:

2