```d
import std;
auto abc(T)(auto ref T a, auto ref T b){
return a+b;
}
auto def(T)(auto ref T a, auto ref T b){
return a*b;
}
alias macro_1 = abc;
void main()
{
writeln(macro_1(15, 20));
alias macro_1 = def;// is this NOT considered variable
shadowing?
writeln(macro_1(100, 20));
}
```