python 3 继承内置 list 对象问题

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)

class AthleteList(list):
    def __int__(self,a_name,a_dob=None,a_times=[]):
        list.__int__([])
        self.name=a_name
        self.dob=a_dob
        self.extend(a_times)
    def top3(self):
        return(sorted(set([sanitize(t)for t in self]))[0:3])

def get_coach_data(filename):
    try:
        with open(filename)as f:
            data=f.readline()
        temp1=data.strip().split(',')
        return(AthleteList(temp1.pop(0),temp1.pop(0),temp1))
    except IOError as ioerr:
        print('File Error:'+str(ioerr))
        return(None)

'''vera=AthleteList('vera vi')
vera.append('1.31')
print(vera.top3())
vera.extend(['2.22','1-21','2:22'])
print(vera.top3())'''

james=get_coach_data('james2.txt')
print(james.name+"'s fastest times are:"+str(james.top3()))