'<stream start>'
document-start-token()
tag-token(value=("!!" . "set"))
block-mapping-start-token()
'?'
scalar-token(plain=#t, style=#f, value="Mark McGwire")
'?'
scalar-token(plain=#t, style=#f, value="Sammy Sosa")
'?'
scalar-token(plain=#t, style=#f, value="Ken Griff")
block-end-token()
'<stream end>'