nl_tokens: ### setIn
pl_tokens: function setIn ( o , path , value ) { if ( path . length ) { var key = path [ 0 ] ; var rest = path . slice ( 1 ) ; if ( typeof key === 'number' && ! ( o instanceof immutable . List ) ) { o = new immutable . List ( ) ; } else if ( ! ( o instanceof immutable . Map ) ) { o = new immutable . Map ( ) ; } return o . set ( key , setIn ( o . get ( path [ 0 ] ) , path . slice ( 1 ) , <mask> ) ) ; } else { return immutable . fromJS ( value ) ; } }