Delegate, scope and associative array

[Edwin van Leeuwen via Digitalmars-d-learn]

I'm probably missing something basic, but I am confused by what 
is going on in the following code.

unittest {
    size_t delegate()[size_t] events;
    foreach( i; 1..4 ) {
        events[i] = { return i; };
    }
    writeln( events[1]() ); // This outputs 3
    assert( events[1]() == 1 );
}
I thought that i should be copied from the local scope and 
therefore when I call events[1]() the return value should be 1, 
but in this case it is 3 (it always seems to be the last value of 
i in the loop).

Cheers, Edwin