human
Solve the following python programming problem given the following code:
def _prepare_fields(self, fields = False) : 
    '
        Declaratively add fields to this block.
        self._fields should contain a list of tuples ("type", "name", offset).
        This method will dynamically add corresponding offset and unpacker methods
          to this block.
        Arguments:
        - `fields`: (Optional) A list of tuples to add. Otherwise,
            self._fields is used.
        ' 
    for field in fields : 
        def handler() : 
            f = getattr (self, ('unpack_' + field [0])) 
            return f (* field [2 :]) 
setattr (self, field [1], handler) 
        debug_payload = handler () 
        if isinstance (self, six.text_type) : 
            debug_payload = debug_payload.encode ('utf8') 
else : 
            debug_payload = str (debug_payload) 
debug_payload = binascii.hexlify (debug_payload) 
        g_logger.debug (('(%s) %s\t@ %s\t: %s' % (field [0].upper (), field [1], hex (self.absolute_offset (field [2])), debug_payload))) 
        setattr (self, ('_off_' + field [1]), field [2]) 

    
    

    Fix the buggy line: if isinstance (self, six.text_type) :
assistant
#Here is Python code to fix the buggy line: if isinstance (self, six.

if isinstance (debug_payload, six.text_type) :