AttributeError: 'Athlete' object has no attribute 'top3'

Traceback (most recent call last):
File "C:Libidlelib13.py", line 40, in <module>
print (james.top3())
AttributeError: 'Athlete' object has no attribute 'top3'

class Athlete:
    def __init__ (self,a_name,a_dob = None,a_times =[]):
        self.name = a_name
        self.dob = a_dob
        self.times  = a_times

def top(self):
    return(sorted(set([sanitize(t) for t in self.times]))[0:3])

    
def sanitize(time_string):
    if '-' in time_string:
        splitter = '-'
    elif ':' in time_string:
        splitter = ':'
    else :
        return (time_string)
    (mins,secs) = time_string.split(splitter)
    return (mins + '.' +secs)

def get_coach_data (filename):
    try:
        with open (filename) as f:
            data =f.readline()
        templ = data.strip().split(',')
        return(Athlete(templ.pop(0),templ.pop(0),templ))
    except IOError as ioerr:
        print('File Error' + str(ioerr))
        return(None)

def add_time(self,time_value):
    self.times.append(time_value)

def add_times(self,list_of_times):
    self.times.extend(list_of_tiems)

james = get_coach_data('james2.txt')  
print (str(james.top()))

修改错误的方法    ：

class Athlete:
    def __init__ (self,a_name,a_dob = None,a_times =[]):
        self.name = a_name
        self.dob = a_dob
        self.times  = a_times

    def top(self):
        return(sorted(set([sanitize(t) for t in self.times]))[0:3])

def top3(self) 前面加Tab

格式！！！