code: func ComputeDistance(a *coordinate.Coordinate, b *coordinate.Coordinate) float64 {
  	if a == nil || b == nil {
  		return math.Inf(1.0)
  	}
  
  	return a.DistanceTo(b).Seconds()
  }
docs: // ComputeDistance returns the distance between the two network coordinates in
  // seconds. If either of the coordinates is nil then this will return positive
  // infinity.