Macro define_report_macros 

macro_rules! define_report_macros {
    {
    # $title_1:tt
    LEVEL
    # $title_2:tt

    $D:tt
    $( [$($flag:tt)*] $level:ident )*
} => { ... };
}

Define a macro $level_report

The title line for the doc comment will be $title_1 `LEVEL` $title_2

A standard body, containing a set of examples, will be provided.

You must pass a dollar sign for D, because there is no dollar escaping mechanism for macro_rules macros in stable Rust (!)