def start(self):
for config_class in self.watched_configurables:<EOL><INDENT>monitor = ConfigFileMonitor(config_class, self.config_dir)<EOL>self.observers.append(<EOL>monitor.start(<EOL>self.add_configurable,<EOL>self.update_configurable,<EOL>self.remove_configurable<EOL>)<EOL>)<EOL><DEDENT>wait_on_event(self.shutdown)<EOL>
Iterates over the `watched_configurabes` attribute and starts a
config file monitor for each.  The resulting observer threads are
kept in an `observers` list attribute.