check if global variable used

checkglobal.py

import dis, builtins

def checkglobal(f):
    for op in dis.Bytecode(f):
        if op.opname == 'LOAD_GLOBAL':
            if not hasattr(builtins, op.argval):
                print(f"Referring global variable {op.argval}")
    return f

@checkglobal
def test():
    x