tkinter TypeError: аргумент write () должен быть str, а не DataFrame

Question

def func4(df1,df2):
    df = pd.concat([df1,df2])
    file = filedialog.asksaveasfile(filetypes = (("csv files","*.csv"),("all files","*.*")))
    file.write(df)
    file.close()

func4(test,train)