code: def open_imports(self, options, loaded_schemata):
          
          for imp in self.imports:
              imported = imp.open(options, loaded_schemata)
              if imported is None:
                  continue
              imported.open_imports(options, loaded_schemata)
              log.debug("imported:\n%s", imported)
              self.merge(imported)
docs: Instruct all contained L{sxbasic.Import} children to import all of
          their referenced schemas. The imported schema contents are I{merged}
          in.
  
          @param options: An options dictionary.
          @type options: L{options.Options}
          @param loaded_schemata: Already loaded schemata cache (URL --> Schema).
          @type loaded_schemata: dict