code: func yaml_parser_parse_block_mapping_value(parser *yaml_parser_t, event *yaml_event_t) bool {
  	token := peek_token(parser)
  	if token == nil {
  		return false
  	}
  	if token.typ == yaml_VALUE_TOKEN {
  		mark := token.end_mark
  		skip_token(parser)
  		token = peek_token(parser)
  		if token == nil {
  			return false
  		}
  		if token.typ != yaml_KEY_TOKEN &&
  			token.typ != yaml_VALUE_TOKEN &&
  			token.typ != yaml_BLOCK_END_TOKEN {
  			parser.states = append(parser.states, yaml_PARSE_BLOCK_MAPPING_KEY_STATE)
  			return yaml_parser_parse_node(parser, event, true, true)
  		}
  		parser.state = yaml_PARSE_BLOCK_MAPPING_KEY_STATE
  		return yaml_parser_process_empty_scalar(parser, event, mark)
  	}
  	parser.state = yaml_PARSE_BLOCK_MAPPING_KEY_STATE
  	return yaml_parser_process_empty_scalar(parser, event, token.start_mark)
  }
docs: // Parse the productions:
  // block_mapping        ::= BLOCK-MAPPING_START
  //
  //                          ((KEY block_node_or_indentless_sequence?)?
  //
  //                          (VALUE block_node_or_indentless_sequence?)?)*
  //                           ***** *
  //                          BLOCK-END
  //
  //