Function shape 

pub fn shape(
    face: &hb_font_t<'_>,
    features: &[Feature],
    buffer: UnicodeBuffer,
) -> GlyphBuffer

Shapes the buffer content using provided font and features.

Consumes the buffer. You can then run GlyphBuffer::clear to get the UnicodeBuffer back without allocating a new one.

If you plan to shape multiple strings using the same [Face] prefer shape_with_plan. This is because [ShapePlan] initialization is pretty slow and should preferably be called once for each [Face].