error

    import copy
class Text(object):
def __init__(self, current_text=""):
    self.current_text = current_text
def getx(self):
    return self.current_text
def write(self,newtext):
    if '[' in self. current_text:
        number=self.current_text.rindex('[')
        self.current_text= self.current_text[0:number]+newtext+self.current_text[number::]
    else:
        self.current_text=self.current_text+newtext
    return self.current_text
def set_font(self, font):
    self.current_text="["+font+"]"+self.current_text+"["+font+"]"
    return self.current_text
def show(self):
    return self.current_text
def restore(self, version): 
     self.current_text =  version
     return  self.current_text
def __str__(self):
    return str(self.current_text)

class SavedText(object):
   def __init__(self, saved=[]):
   self.saved =[]
   def getu(self):
   return self.saved
   def save_text(self, document):
   Originator.set(copy.copy(document))
   self.saved.append(Originator.save_to_memento())

   def get_version(self, number):
   return self.saved[number]
 def __str__(self):
    return str(self.saved) 

class Memento(object):
    def __init__(self, state):
    self._state = state

def get_saved_state(self):
    return self._state
   def __str__(self):
     return '"' +str(self._state) +'"'

class Originator(object):
_state = ""

def set(self, state):
    self._state = state

def save_to_memento(self):
    return Memento(self._state)

def restore_from_memento(self, memento):
    self._state = memento.get_saved_state()


Originator=Originator()

checkio says that there is a TypeError: <class 'dict'> is wrong data type , i dont understand what i did wrong