code: def init_config(self, app):
          
          app.config.setdefault(
              'OAISERVER_BASE_TEMPLATE',
              app.config.get('BASE_TEMPLATE',
                             'invenio_oaiserver/base.html'))
  
          app.config.setdefault(
              'OAISERVER_REPOSITORY_NAME',
              app.config.get('THEME_SITENAME',
                             'Invenio-OAIServer'))
  
          # warn user if ID_PREFIX is not set
          if 'OAISERVER_ID_PREFIX' not in app.config:
              import socket
              import warnings
  
              app.config.setdefault(
                  'OAISERVER_ID_PREFIX',
                  'oai:{0}:recid/'.format(socket.gethostname()))
              warnings.warn(
                  """Please specify the OAISERVER_ID_PREFIX configuration."""
                  """default value is: {0}""".format(
                      app.config.get('OAISERVER_ID_PREFIX')))
  
          for k in dir(config):
              if k.startswith('OAISERVER_'):
                  app.config.setdefault(k, getattr(config, k))
docs: Initialize configuration.
  
          :param app: An instance of :class:`flask.Flask`.