python convert two lists with duplicates to dictiona

dict_1={}

for key,value in zip(list_one,list_two):
    if key not in dict_1:
        dict_1[key]=[value]
    else:
        dict_1[key].append(value)

print(dict_1)

{'a': [1, 2], 'd': [4], 'c': [3]}