But the fact is, when Python compiles the body of the function, it decides that b is a local variable because it is assigned within the function. The generated bytecode reflects this decision and will try to fetch b from the local scope. Later, when the call f2(3) is made, the body of f2 fetches and prints the value of the local variable a, but when trying to fetch the value of local variable b, it discovers that b is unbound.
