Defined Functions batch modify file

def func(file, old, new):
    import os
    with open(file,mode="r",encoding="utf-8") as f1,\
    open("file_副本",mode="w",encoding="utf-8") as f2:
        for line in f1:
            if old in line:
                line = line.replace(old,new)
                f2.write(line)
            else:
                f2.write(line)
    os.remove(file)
    os.rename("file_副本",file)
func("11.txt","老男孩","goodboy")