Closure late binding

Question

Accepted Answer

Closures in Python capture variables by reference, not by value. All three functions close over the same i variable in the enclosing (global here) scope. By the time any of them are called, the loop has finished and i is 2, so every function returns 2. The fix is to force capture by value using a default argument: def f(i=i): return i. Default arguments are evaluated at definition time, so each function gets its own snapshot of i.