Macro DefProtocolFormat 

macro_rules! DefProtocolFormat {
    ($pf_name: ident for $struct_name: ident { $($val: ident <- $fmt: expr),* }) => { ... };
    ($vis: vis $pf_name: ident for $struct_name: ident { $($val: ident <- $fmt: expr),* }) => { ... };
}

Defines Format Fragment implementation for a structure