{
  ? complex key: value
}
# STREAM_START                                  FYTT_STREAM_START
# FLOW_MAPPING_START                            FYTT_FLOW_MAPPING_START
# KEY                                           FYTT_KEY
# SCALAR value='complex key' style=PLAIN        FYTT_KEY
# VALUE                                         FYTT_SCALAR value='complex key' style=PLAIN
# SCALAR value='value' style=PLAIN              FYTT_VALUE
# FLOW_MAPPING_END                              FYTT_SCALAR value='value' style=PLAIN
# STREAM_END                                    FYTT_FLOW_MAPPING_END
#                                               FYTT_STREAM_END