def span_to(spanner)
      Vector.new((@x - spanner.x).abs, (@y - spanner.y).abs)
    end
def span_to(spanner)
      Vector.new((@x - spanner.x).abs, (@y - spanner.y).abs)
    end
Find the span between two Vectors

 * *Args*    :
   - +spanner+ -> Vector

 * *Returns* :
   - Vector