python的类型转化

问题遇到的现象和发生背景

下面这个文件名为filename，将其转化为字典

def load_road_network(filename):
    dict1=dict()
    dict2=dict()
    add1=0
    add2=0
    with open('filename','r') as file:
        for line in file:
            line=line.strip()
            if line:
                if '#Intersection' in line:
                    lst=[]
                    key=line.split(':')[1]
                    add1=1
                elif '#Roads' in line:
                    lst=[]
                    add2=1
                elif add1:
                    lst.append([eval(x) for x in line.split(';')])
                elif add2:
                    s=line.split(':')
                    dict2[eval(s[0])]=eval(s[1])
            elif add1:
                dict1[int(key)]=lst
                add1=0
    res=(dict1,dict2)
    return res