Tests whether the range R has lvalue elements. These are defined as elements that can be passed by reference and have their address taken. The following code should compile for any range with lvalue elements.

void passByRef(ref ElementType!R stuff);
...
static assert(isInputRange!R);
passByRef(r.front);
static if (isBidirectionalRange!R) passByRef(r.back);
static if (isRandomAccessRange!R) passByRef(r[0]);