def dropbox_factory(request):
try:<EOL><INDENT>return request.registry.settings['<STR_LIT>'].get_dropbox(request.matchdict['<STR_LIT>'])<EOL><DEDENT>except KeyError:<EOL><INDENT>raise HTTPNotFound('<STR_LIT>')<EOL><DEDENT>
expects the id of an existing dropbox and returns its instance