Macro count 

macro_rules! count {
    () => { ... };
    ($x0:tt $x1:tt $x2:tt $x3:tt $x4:tt $x5:tt $x6:tt $x7:tt
     $x8:tt $x9:tt $x10:tt $x11:tt $x12:tt $x13:tt $x14:tt $x15:tt $($xs:tt)*) => { ... };
    ($x0:tt $x1:tt $x2:tt $x3:tt $x4:tt $x5:tt $x6:tt $x7:tt $($xs:tt)*) => { ... };
    ($x0:tt $x1:tt $x2:tt $x3:tt $($xs:tt)*) => { ... };
    ($x0:tt $x1:tt $($xs:tt)*) => { ... };
    ($x0:tt $($xs:tt)*) => { ... };
}

A macro used internally to MinecraftRS to count the number of tokens you give to the macro and return the count as usize.