code: func (b *Bound) Union(other *Bound) *Bound {
  	b.Extend(other.SouthWest())
  	b.Extend(other.NorthWest())
  	b.Extend(other.SouthEast())
  	b.Extend(other.NorthEast())
  
  	return b
  }
docs: // Union extends this bounds to contain the union of this and the given bounds.