Location\Distance\DistanceInterface::getDistance PHP Method

    public function getDistance(Coordinate $point1, Coordinate $point2);

 /**
  * Calculates the length of the line (distance between the two
  * coordinates).
  *
  * @param DistanceInterface $calculator instance of distance calculation class
  *
  * @return float
  */
 public function getLength(DistanceInterface $calculator)
 {
     return $calculator->getDistance($this->point1, $this->point2);
 }