def METHOD_NAME(self):
    if not isinstance(self.cffobj, dict):
        raise ValueError("Expected cffobj to be of type 'dict'.")
    if "cff-version" not in self.cffobj.keys():
        raise ValueError("Missing key 'cff-version' in CITATION.cff file.")
    if self.cffobj["cff-version"] not in self.supported_cff_versions:
        raise ValueError(f"'cff-version': '{self.cffobj['cff-version']}' isn't a supported version.")