public void WriteHead(TextWriter output)
        {
            m_emitter          = new Emitter(output, IsFormatKeys);
            m_isWriteSeparator = false;

            if (IsWriteVersion)
            {
                m_emitter.WriteMeta(MetaType.YAML, Version.ToString());
                m_isWriteSeparator = true;
            }

            if (IsWriteDefaultTag)
            {
                m_emitter.WriteMeta(MetaType.TAG, DefaultTag.ToHeaderString());
                m_isWriteSeparator = true;
            }
            foreach (YAMLTag tag in m_tags)
            {
                m_emitter.WriteMeta(MetaType.TAG, tag.ToHeaderString());
                m_isWriteSeparator = true;
            }
        }