human
Solve the following python programming problem given the following code:
def _helper_csv(self, writer, na_rep = None, cols = None, header = True, index = True, index_label = None, float_format = None, date_format = None) : 
    if (cols is None) : 
        cols = self.columns 
has_aliases = isinstance (header, (tuple, list, np.ndarray, Index)) 
    if (has_aliases or header) : 
        if index : 
            if (index_label is not False) : 
                if (index_label is None) : 
                    if isinstance (self.obj.index, MultiIndex) : 
                        index_label = [] 
                        for (i, name) in enumerate (self.obj.index.names) : 
                            if (name is None) : 
                                name = '' 
index_label.append (name) 
else : 
                        index_label = self.obj.index.name 
                        if (index_label is None) : 
                            index_label = [''] 
else : 
                            index_label = [index_label] 
else : 
                    if (not isinstance (index_label, (list, tuple, np.ndarray, Index))) : 
                        index_label = [index_label] 
encoded_labels = list (index_label) 
else : 
                encoded_labels = [] 
if has_aliases : 
                if (len (header) != len (cols)) : 
                    raise ValueError (('Writing %d cols but got %d aliases' % (len (cols), len (header)))) 
else : 
                    write_cols = header 
else : 
                write_cols = cols 
encoded_cols = list (write_cols) 
            writer.writerow ((encoded_labels + encoded_cols)) 
else : 
            encoded_cols = list (cols) 
            writer.writerow (encoded_cols) 
if (date_format is None) : 
        date_formatter = (lambda x : Timestamp (x)._repr_base) 
else : 
        def strftime_with_nulls(x) : 
            x = Timestamp (x) 
            if notnull (x) : 
                return x.strftime (date_format) 
date_formatter = (lambda x : strftime_with_nulls (x)) 
data_index = self.obj.index 
    if isinstance (self.obj.index, PeriodIndex) : 
       ...

    
    

    Fix the buggy line: for (j, idx) in enumerate (idx) :
assistant
#Here is Python code to fix the buggy line: for (j, idx) in enumerate (idx) :
.

for (j, idx) in enumerate (data_index) :