Function fig_embed_insert_key 

pub unsafe extern "C" fn fig_embed_insert_key(
    fm: *mut FigEmbed,
    path: *const FigPathSegment,
    path_len: usize,
    key: *const u8,
    key_len: usize,
    val: *const u8,
    val_len: usize,
) -> FigStatus