What is the utility of .stringof with expressions?

[Shriramana Sharma via Digitalmars-d]

D currently supports:

writeln((1 + 2).stringof);

to print:

1 + 2

What is the real-world use case of this "feature"? I mean, everyone knows 
what the code they write looks like, so why would they want to have a 
language feature to get a string representation of it that they can print 
out to the user? I mean, if at all someone wants to print out 1 + 2, they 
can always say "1 + 2" and be done with it, instead of going to the 
convolution of .stringof...

One thing I observe however is that:

    writeln((1+ 2).stringof);
    writeln((1 +2).stringof);
    writeln((1  +  2).stringof);

all print "1 + 2" (without the quotes) so it's not a simple compiler dumps 
to string thing, but still I don't understand what this can be useful for...

-- 
Shriramana Sharma, Penguin #395953