conflcits.js

        let conflicts = _.chain( shaders ).reduce( ( memo, shader ) => {
            return memo.concat(
                shader.runtime.metadata.fragment.variables,
                shader.runtime.metadata.vertex.variables
            );
        }, [] ).countBy().reduce( ( memo, countGroup, name ) => {
            if( countGroup > 1 ) {
                memo.push( name );
            }
            return memo;
        }, [] ).value();