Macro tuple_conversion

macro_rules! tuple_conversion {
    ($name:ident, 1, [$($bit:tt:$num:tt),*]) => { ... };
    ($name:ident, 2, [$($bit:tt:$num:tt),*]) => { ... };
    ($name:ident, 3, [$($bit:tt:$num:tt),*]) => { ... };
    ($name:ident, 4, [$($bit:tt:$num:tt),*]) => { ... };
}