old_contents: class Database(object):
      def __init__(self, channels):
          self.userdb = {}
          for i in channels:
              self.userdb[i] = {}
  
      def removeEntry(self, event, nick):
          try:
              del self.userdb[event.target][nick]
          except KeyError:
              for i in self.userdb[event.target].values():
                  if i['host'] == event.source.host:
                      del self.userdb[event.target][i['hostmask'].split("!")[0]]
                      break
  
      def addEntry(self, channel, nick, hostmask, host, account):
          self.userdb[channel][nick] = {
              'hostmask': hostmask,
              'host': host,
              'account': account
          }
  
      __getitem__ = self.userdb.__getitem__
      __delitem__ = self.userdb.__delitem__
      __setitem__ = self.userdb.__setitem__
      __str__ = self.userdb.__str__
  
      get = self.userdb.get
      keys = self.userdb.keys
  
new_contents: class Database(object):
      def __init__(self, channels):
          self.userdb = {}
          for i in channels:
              self.userdb[i] = {}
          self.__getitem__ = self.userdb.__getitem__
          self.__delitem__ = self.userdb.__delitem__
          self.__setitem__ = self.userdb.__setitem__
          self.__str__ = self.userdb.__str__
          self.get = self.userdb.get
          self.keys = self.userdb.keys
  
      def removeEntry(self, event, nick):
          try:
              del self.userdb[event.target][nick]
          except KeyError:
              for i in self.userdb[event.target].values():
                  if i['host'] == event.source.host:
                      nick = i['hostmask'].split("!")[0]
                      del self.userdb[event.target][nick]
                      break
  
      def addEntry(self, channel, nick, hostmask, host, account):
          self.userdb[channel][nick] = {
              'hostmask': hostmask,
              'host': host,
              'account': account
          }
  
subject: Fix undefined variables