Macro metron_core::def_unit

macro_rules! def_unit {
    ( $vis:vis $unit_name:ident; ) => { ... };
    ( $vis:vis $unit_name:ident {
        $(from $from_body:tt ,)*
        // $(into $into_body:tt ,)*
        $(exp   $exp_body:tt ,)*
        $(sym   $sym_body:tt ,)?
        // $(qua   $qua_body:tt ,)?
        // $(dim   $dim_body:tt ,)?
    }) => { ... };
    ( $vis:vis $scale_name:ident |: $base_unit:ty => $unit_exp_name:ident; ) => { ... };
    ( $vis:vis $scale_name:ident |: $base_unit:ty => $unit_exp_name:ident {
        $(from $from_body:tt ,)*
        $(sym   $sym_body:tt ,)?
    } ) => { ... };
    ( $lhs:ty |* $rhs:ty => $vis:vis $mul:ident; ) => { ... };
    ( $lhs:ty |* $rhs:ty => $vis:vis $mul:ident {
        $(from $from_body:tt ,)*
        $(exp   $exp_body:tt ,)*
        $(sym   $sym_body:tt ,)?
    } ) => { ... };
    ( $lhs:ty |/ $rhs:ty => $vis:vis $div:ident; ) => { ... };
    ( $lhs:ty |/ $rhs:ty => $vis:vis $div:ident {
        $(from $from_body:tt ,)*
        $(exp   $exp_body:tt ,)*
        $(sym   $sym_body:tt ,)?
    } ) => { ... };
}