def __str__ ( self ) :
    text = "str" . format ( len ( self . dispersions )
    for i in range ( len ( self . dispersions ) ) :
        d = self . dispersions [ i ]
        s = self . spins [ i ]
        text += "str" . format ( s + 1 , d . __str__ ( ) )
    return text

def __str__ ( self ) :
    text = "str" . format ( len ( self . dispersions ) )
    for i in range ( len ( self . dispersions ) ) :
        d = self . dispersions [ i ]
        s = self . spins [ i ]
        text += "str" . format ( s + 1 , d . __str__ ( ) )
    return text

次に示すpythonコードの誤りを修正しなさい。