code: public function interpolate($x, $y, array $elevationOnBoundingBox)
      {
          $this->checkArguments($x, $y, $elevationOnBoundingBox);
  
          return $this->Lambda->__invoke($x, $y, $elevationOnBoundingBox);
      }
docs: Interpolate.
  
  p0------------p1
  |      |
  |      y
  |      |
  |--x-- Z
  |
  p2------------p3
  
  @param  float                    $x                      x position of Z within bounding box, required: $x in [0.0, 1.0]
  @param  float                    $y                      y position of Z within bounding box, required: $y in [0.0, 1.0]
  @param  array                    $elevationOnBoundingBox elevation data on [p0, p1, p2, p3]
  @return int                      estimated elevation on point Z
  @throws InvalidArgumentException