Macro implements 

macro_rules! implements {
    ( $( $arg : tt )+ ) => { ... };
}

Macro implements to answer the question: does it implement a trait?

Basic use-case.

use implements::*;
dbg!( implements!( 13_i32 => Copy ) );
// < implements!( 13_i32 => Copy ) : true
dbg!( implements!( Box::new( 13_i32 ) => Copy ) );
// < implements!( 13_i32 => Copy ) : false