How to force evaluation of range?

[Taylor Hillegeist via Digitalmars-d-learn]

So I have this code and I have to add the element
.each!(a => a.each!("a"));
to the end in order for it to evaluate the range completely and 
act like I expect it too. Is there a  better thing to put in the 
place of
.each!(a => a.each!("a"));?
import std.stdio;
import std.path;
import std.file;
import std.uni;
import std.range;
import std.conv;
import std.algorithm;

void main(string[] Args){

    assert(Args.length>1,"Need a path to source files");
    assert(Args[1].isValidPath,"Path given is not Valid!");

    dirEntries(Args[1], SpanMode.depth)
        .filter!(f => f.name.endsWith(".c",".h"))
        .tee!(a => writeln("\n",a,"\n\t","=".repeat(80).join))
        .map!(a => a
            .File("r")
            .byLine
            .enumerate
            .filter!( l => l.value.byGrapheme.walkLength > 80)
            .tee!(a => writeln("Line: ",a.index,"\t",a.value))
         ).each!(a => a.each!("a")); //Force evaluation of every 
item

}