You can do that on command line, too
% yamlpp5-highlight data/example.yaml
---
- list
- items
- key 1: one
key 2: two
- { flow: mapping }
%
% yamlpp5-highlight data/invalid.yaml
---
- list
- items
- key 1: one
key 2: two
- [ flow, sequence }
- [ another ]
Line : 6
Message : Expected (EOL FLOWSEQ_END FLOW_COMMA WS), but got FLOWMAP_END
Where : /home/tina/develop/github/YAML-PP-p5/lib/YAML/PP/Parser.pm line 487
YAML : "}"
at /home/tina/develop/github/YAML-PP-p5/lib/YAML/PP/Loader.pm line 52.
%