page.go
func (f Font) Widths() []float64 {
	x := f.V.Key("Widths")
	var out []float64
	for i := 0; i < x.Len(); i++ {
		out = append(out, x.Index(i).Float64())
	}
	return out
}
func (f Font) Widths() []float64 {
	x := f.V.Key("Widths")
	var out []float64
	for i := 0; i < x.Len(); i++ {
		out = append(out, x.Index(i).Float64())
	}
	return out
}
// Widths returns the widths of the glyphs in the font.
// In a well-formed PDF, len(f.Widths()) == f.LastChar()+1 - f.FirstChar().