def _add_referencer(registry):
referencer = registry.queryUtility(IReferencer)<EOL>if referencer is not None:<EOL><INDENT>return referencer<EOL><DEDENT>ref = registry.settings['<STR_LIT>']<EOL>url = registry.settings['<STR_LIT>']<EOL>r = DottedNameResolver()<EOL>registry.registerUtility(r.resolve(ref)(url), IReferencer)<EOL>return registry.queryUtility(IReferencer)<EOL>
Gets the Referencer from config and adds it to the registry.