multiplier def set to None ,will be 0 is better

[bluescity]

sorry, i dont understand english.
if you set parameter tries , parameter can not be None(it's def ,it's be 0 better

error code :
import robobrowser
r = robobrowser.RoboBrowser(tries=3)
r.open("http://www.gosdfagle.com") #any not exist site

to fix this:
file: browser.py
line 70:
def init(self, session=None, parser=None, user_agent=None,
history=True, timeout=None, allow_redirects=True, cache=False,
cache_patterns=None, max_age=None, max_count=None, tries=None,
multiplier=None):
change to:
def init(self, session=None, parser=None, user_agent=None,
history=True, timeout=None, allow_redirects=True, cache=False,
cache_patterns=None, max_age=None, max_count=None, tries=None,
multiplier=0):