+STR
+DOC
+SEQ
=VAL <tag:yaml.org,2002:str> :
+MAP
=VAL <tag:yaml.org,2002:null> :
=VAL :a
=VAL :b
=VAL <tag:yaml.org,2002:str> :
-MAP
+MAP
=VAL <tag:yaml.org,2002:str> :
=VAL <tag:yaml.org,2002:null> :
-MAP
-SEQ
-DOC
-STR
