[Python] defaultdict with default value 1?

I read an implementation of counting sort:

from collections import defaultdict
def sort_colors(A):
ht = {} # a hash map
ht = defaultdict(lambda:0, ht) # with default value 1
for i in A:
ht += 1
ret = []
for k in [0, 1, 2]:
ret.extend([k]*ht[k])
return ret


In the first two lines of the func:

ht = {}
ht = defaultdict(lambda:0, ht)


I am not clear about this initialization. Shall we just replace these two lines with following?

ht = defaultdict(int) # default value 0

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