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import std.experimental.all;
struct FibonacciRange
{
int a = 1, b = 1;
enum empty = false;
int front() const {
return a;
}
void popFront() {
auto t = a;
a = b;
b = t + b;
}
}
void main()
{
FibonacciRange fib;
fib.take(10).writeln;
}