code: def _calc_xy(self, xxx_todo_changeme, angle, length):
          
          (x, y) = xxx_todo_changeme
          return (x+(cos(radians(angle))*length),
                  y+(sin(radians(angle))*length))
docs: Calculates the coordinates after a specific saccade was made.
          
          Parameters:
              (x,y) : tuple of floats or ints
                  The coordinates before the saccade was made
              angle : float or int
                  The angle that the next saccade encloses with the 
                  horizontal display border
              length: float or int
                  The length of the next saccade