Function math_content 

pub fn math_content(
    tex: &str,
    display: bool,
    caption: &str,
    r: &Rendered,
    mxc: &str,
    reply_to: Option<&str>,
) -> Value

The m.image content for a rendered formula uploaded to mxc, without the mxblocks payload (write with_caption’s under the content key). caption: text to go with the formula, if any; reply_to: an event to reply to.