Converting YAML to JSON with Python: <block end> ​​found

I am trying to convert the following example yaml

file tojson

test.yaml

- fields: {name: "Test", nr: "000"}
    model: testmodel
    pk: "1"

      

        
        
        
      

    

However, the challenge

python -c 'import sys, yaml, json; json.dump(yaml.load(sys.stdin), 
sys.stdout, indent=4)' < test.yaml > test.json

      

        
        
        
      

    

returns an error

"expected <block end>, but found %r" % token.id, token.start_mark)
yaml.parser.ParserError: while parsing a block mapping
  in "<stdin>", line 1, column 3
expected <block end>, but found '<block mapping start>'
  in "<stdin>", line 3, column 5

      

        
        
        
      

    

What's wrong with my yaml file?