human
Solve the following python programming problem given the following code:
def __unicode__(self) : 
    lines = [] 
    def add_row(row) : 
        cols = ['{:>2}'.format (row [0]), '{:^18}'.format (row [1]), '{:^21}'.format (row [2])] 
        cols.extend (('{:^27}'.format (unicode (val)) for val in row [3 :])) 
        lines.append ('|'.join (cols)) 
add_row (add_row.headers) 
    lines.append (('-' * len (lines [0]))) 
    map (add_row, self.rows) 
    return '
'.join (lines) 

    
    

    Fix the buggy line: add_row (add_row.headers)
assistant
#Here is Python code to fix the buggy line: add_row (add_row.

add_row (self.headers)