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=VAL <tag:yaml.org,2002:str> :
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=VAL <tag:yaml.org,2002:null> :
=VAL :a
=VAL :b
=VAL <tag:yaml.org,2002:str> :
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=VAL <tag:yaml.org,2002:str> :
=VAL <tag:yaml.org,2002:null> :
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