Function placeholder_html_placed 

pub fn placeholder_html_placed(
    state: Readiness,
    message: &str,
    action: Option<Markup<'_>>,
    opts: &Emit,
    out: &mut String,
    placed: &mut Option<Range<usize>>,
)

A placeholder, saying where the way out landed.

Byte-identical to placeholder_html_into, and where there is a way out it sets placed to the offsets in out between which the whole placeholder-action block was written – the wrapper included, since the wrapper is what goes with it. None stays None when there is no action.

Same reason as the other placed forms in this crate: a caller compiling this markup into a template has to know which bytes the way out produced, and the way out is a caller-supplied string that may appear elsewhere in the document.