'verify_nameservers' object has no attribute 'pid'

[jacobStankaitis]

Traceback (most recent call last):
  File "subbrute.py", line 700, in run
    killproc(pid = verify_nameservers_proc.pid)
AttributeError: 'verify_nameservers' object has no attribute 'pid'

During handling of the above exception, another exception occurred

Traceback (most recent call last):
  File "subbrute.py", line 834, in <module>
    print_target(target, record_type, options.subs, options.resolv
output)
  File "subbrute.py", line 513, in print_target
    for result in run(target, query_type, subdomains, resolve_list
  File "subbrute.py", line 703, in run
    verify_nameservers_proc.end()
AttributeError: 'verify_nameservers' object has no attribute 'end'

I'm getting this on python 3.7.2 while running python subbrute.py -t x.txt > out on carnegiescience.edu or when it was transitioning to www.tesla.com. Script was ran on Win 7 Ultimate SP1 and it was his 1st or 2nd line.