Function ytext_format 

#[unsafe(no_mangle)]
pub unsafe extern "C" fn ytext_format(
    txt: *const Branch,
    txn: *mut Transaction,
    index: u32,
    len: u32,
    attrs: *const YInput,
)

Wraps an existing piece of text within a range described by index-len parameters with formatting blocks containing provided attrs metadata. attrs must be a map-like type.