some past verbs doesn't convert to its root corectly

[nillllllllllll]

I use your python package and I change the value of "enableVerb" to True value to test the verb input.
from PersianStemmer import PersianStemmer
ps = PersianStemmer()
print(ps.run("رفتند"))
It prints "رو" which is not correct

print(ps.run("رفت"))
It prints "رفت" which is correct