code: func (b *Bound) Pad(amount float64) *Bound {
  	b.sw.SetX(b.sw.X() - amount)
  	b.sw.SetY(b.sw.Y() - amount)
  
  	b.ne.SetX(b.ne.X() + amount)
  	b.ne.SetY(b.ne.Y() + amount)
  
  	return b
  }
docs: // Pad expands the bound in all directions by the amount given. The amount must be
  // in the units of the bounds. Technically one can pad with negative value,
  // but no error checking is done.