nl_tokens: / * Return an edge from the tree with a negative cut value or null if there is none .
pl_tokens: function leaveEdge ( tree ) { var edges = tree . edges ( ) ; for ( var n <mask> edges ) { var e = edges [ n ] ; var treeValue = tree . edge ( e ) ; if ( treeValue . cutValue < 0 ) { return e ; } } return null ; }