* Returns the specified distance between two agents.
* distance is one of the four distance functions supported by HASH,
* defaults to manhattan distance.
* @param a
* @param b
* @param distance
distanceBetween(agent, agent, distanceFunction = "manhattan")
/** Returns the unit vector of a vector
* @param vec an array of numbers
normalizeVector(vec: number[])
* Returns a position array of x,y,z is set to true
* @param topology the Context.globals().topology object
* @param z_plane defaults to false
randomPosition(topology: topology object, z_plane = false)