code: def view_vector(self, vector, viewup=None):
          
          focal_pt = self.center
          if viewup is None:
              viewup = rcParams['camera']['viewup']
          cpos = [vector + np.array(focal_pt),
                  focal_pt, viewup]
          self.camera_position = cpos
          return self.reset_camera()
docs: Point the camera in the direction of the given vector