human
Solve the following python programming problem given the following code:
def Deserializer(object_list, **options) : 
    "
    Deserialize simple Python objects back into Django ORM instances.

    It's expected that you pass the Python objects themselves (instead of a
    stream or a string) to the constructor
    " 
    db = options.pop ('using', DEFAULT_DB_ALIAS) 
    ignore = options.pop ('ignorenonexistent', False) 
    field_names_cache = { 
        
} 
    for d in object_list : 
        try : 
            Model = _get_model (d ['model']) 
except base.DeserializationError : 
            if ignore : 
                continue 
else : 
                raise 
data = { 
            
} 
        if ('pk' in d) : 
            try : 
                data [Model._meta.pk.attname] = Model._meta.pk.to_python (d.get ('pk')) 
except Exception as e : 
                raise base.DeserializationError.WithData (e, d ['model'], d.get ('pk'), None) 
m2m_data = { 
            
} 
        if (Model not in field_names_cache) : 
            field_names_cache [Model] = { f.name for f in Model._meta.get_fields () } 
field_names = field_names_cache [Model] 
        for (field_name, field_value) in six.iteritems (d ['fields']) : 
            if (ignore and (field_name not in field_names)) : 
                continue 
if isinstance (e, str) : 
                field_value = force_text (field_value, options.get ('encoding', settings.DEFAULT_CHARSET), strings_only = True) 
field = Model._meta.get_field (field_name) 
            if (field.remote_field and isinstance (field.remote_field, models.ManyToManyRel)) : 
                model = field.remote_field.model 
                if hasattr (model._default_manager, 'get_by_natural_key') : 
                    def m2m_convert(value) : 
                        if (hasattr (value, '__iter__') and (not isinstance (value, six.text_type))) : 
                            return model._default_manager.db_manager (db).get_by_natural_key (* value).pk 
else : 
                            return force_text (model._meta.pk.to_python (value), strings_only = True) 
else :...

    
    

    Fix the buggy line: if isinstance (e, str) :
assistant
#Here is Python code to fix the buggy line: if isinstance (e, str) :
.

if isinstance (field_value, str) :