Macro define_binary_op_trait 

macro_rules! define_binary_op_trait {
    ($trait_name:ident, $required_trait:ident, $name:ident, $operator:tt; $($default_dtypes:ty),*) => { ... };
    ($trait_name:ident, $required_trait:ident, $name:ident, $operator:tt) => { ... };
}