Macro element_wise

macro_rules! element_wise {
    ($func:ident, $Op:ident $({$( $(#[$meta: meta])? $var: ident : $var_typ: path),*})?,
        $([$($typ:ident),*] => $f:expr ),*
        $(; q: $( [$($typ_dt:ident),*] => $f_f32:expr),*)?
        $(; cost: $cost:expr )?
        $(; declutter: $declutter:expr )?
        $(; operating_datum_type: $operating_datum_type:expr )?
        $(; prefix: $prefix:expr )?
        $(; quantize: $quantize:expr )?
        $(; validation: $validation:expr )?
    ) => { ... };
}