Macro impl_scalar_lhs_jet2_binop 

macro_rules! impl_scalar_lhs_jet2_binop {
    ($trait:ident, $method:ident, ($l:ident, $r:ident) => $body:expr) => { ... };
    (@one $t:ty, $trait:ident, $method:ident, ($l:ident, $r:ident) => $body:expr) => { ... };
}