Differences between two dates (in days...)

[Mil58 via Digitalmars-d-learn]

Hi All...
I am desperate for the answer to the following problem:
to obtain the difference between the date of today and an older 
date (results in days...)

See my script below, where I would like to do:
"date of today" (var: auj) - "an older date" (var: deb) = xx days

import std.stdio;
import std.datetime;
import core.time : Duration;

void main()
{
auto deb = DateTime(2019, 9, 5);
auto auj = Clock.currTime();
writeln("Aujourd'hui : ", auj.day, " ", auj.month, " ", auj.year);
writeln("Le début : ", deb.day, " ", deb.month, " ", deb.year);
}

Thanks in advance !  :-)