You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: ca.rs
    path of file: ./repos/krill/src/commons/api
    
    the code of the file until where you have to start completion: //! Common data types for Certificate Authorities, defined here so that the CLI

    
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match self {
            ParentKindInfo::Ta => write!(f, "This CA is a TA"),
            ParentKindInfo::Embedded => write!(f, "Embedded parent"),
            ParentKindInfo::Rfc6492 => write!(f, "RFC 6492 Parent"),
        }
    }