abc = 1

def set_global(name, value):
    globals()[name] = value

if __name__ == "__main__":
    set_global("abc", 2)
    print("__main__.abc = %s" % abc)

    import prog
    prog.set_global("abc", 3)
    print("prog.abc     = %s" % prog.abc)
    print("__main__.abc = %s" % abc)