code: def _parseEnv(self, env=None):
          
          if not env:
              env = self._env
          if env.has_key('MUNIN_STATEFILE'):
              self._stateFile = env.get('MUNIN_STATEFILE')
          else:
              self._stateFile = '/tmp/munin-state-%s' % self.plugin_name
          if env.has_key('MUNIN_CAP_DIRTY_CONFIG'):
              self._dirtyConfig = True
docs: Private method for parsing through environment variables.
          
          Parses for environment variables common to all Munin Plugins:
              - MUNIN_STATEFILE
              - MUNIN_CAP_DIRTY_CONFIG
              - nested_graphs
          
          @param env: Dictionary of environment variables.
                      (Only used for testing. initialized automatically by 
                      constructor.