code: def find_existing(self):
          
          sg = self.consul.find_secgroup(self.name)
  
          current = sg.rules
          log.debug('Current rules: %s' % current)
          log.debug('Intended rules: %s' % self.rules)
          exp_rules = []
          for rule in self.rules:
              exp = (
                      rule[A.secgroup.PROTOCOL],
                      rule[A.secgroup.FROM],
                      rule[A.secgroup.TO],
                      rule[A.secgroup.SOURCE],
                      )
              exp_rules.append(exp)
              if exp in current:
                  del current[exp]
              else:
                  self.create_these_rules.append(exp)
  
          self.delete_these_rules.extend(current.itervalues())
  
          log.debug('Create these rules: %s' % self.create_these_rules)
          log.debug('Delete these rules: %s' % self.delete_these_rules)
docs: Finds existing rule in secgroup.
  
          Populates ``self.create_these_rules`` and ``self.delete_these_rules``.