human
Solve the following python programming problem given the following code:
def _format_window(translator, window) : 
    components = [] 
    if (len (window._group_by) > 0) : 
        partition_args = [translator.translate (x) for x in window._group_by] 
        components.append ('PARTITION BY {0}'.format (', '.join (_foll))) 
if (len (window._order_by) > 0) : 
        order_args = [] 
        for expr in window._order_by : 
            key = expr.op () 
            translated = translator.translate (key.expr) 
            if (not key.ascending) : 
                translated += ' DESC' 
order_args.append (translated) 
components.append ('ORDER BY {0}'.format (', '.join (order_args))) 
(p, f) = (window.preceding, window.following) 
    def _prec(p) : 
        return ('{0} PRECEDING'.format (p) if (p > 0) else 'CURRENT ROW') 
def _foll(f) : 
        return ('{0} FOLLOWING'.format (f) if (f > 0) else 'CURRENT ROW') 
if ((p is not None) and (f is not None)) : 
        frame = 'ROWS BETWEEN {0} AND {1}'.format (_prec (p), _foll (f)) 
else : 
        if (p is not None) : 
            if isinstance (p, tuple) : 
                (start, end) = p 
                frame = 'ROWS BETWEEN {0} AND {1}'.format (_prec (start), _prec (end)) 
else : 
                kind = ('ROWS' if (p > 0) else 'RANGE') 
                frame = '{0} BETWEEN {1} AND UNBOUNDED FOLLOWING'.format (kind, _prec (p)) 
else : 
            if (f is not None) : 
                if isinstance (f, tuple) : 
                    (start, end) = f 
                    frame = 'ROWS BETWEEN {0} AND {1}'.format (_foll (start), _foll (end)) 
else : 
                    kind = ('ROWS' if (f > 0) else 'RANGE') 
                    frame = '{0} BETWEEN UNBOUNDED PRECEDING AND {1}'.format (kind, _foll (f)) 
else : 
                frame = None 
if (frame is not None) : 
        components.append (frame) 
return 'OVER ({0})'.format (' '.join (components)) 

    
    

    Fix the buggy line: components.append ('PARTITION BY {0}'.format (', '.join (_foll)))
assistant
#Here is Python code to fix the buggy line: components.

components.append ('PARTITION BY {0}'.format (', '.join (partition_args)))