Returns accessions of root terms of the ontology. For some ontologies these functions might fail when the ontology used was not design to have root classes
返回加入本体根条款的。对于某些本体,这些功能可能会失败时使用本体设计有根类
用法----------Usage----------
getRootIds(object)
参数----------Arguments----------
参数:object
instance of the Ontology class
Ontology类的实例