question: returns the roots of the graph . concode_field_sep List<Node> nodes concode_elem_sep String string concode_elem_sep SortedMap<R,Node> children concode_elem_sep Logger log concode_elem_sep SortedMap<String,V> attributes concode_elem_sep List<Node> roots concode_elem_sep Pattern graphPattern concode_elem_sep V content concode_elem_sep String valueRegex concode_field_sep V getAttrValue concode_elem_sep Set<String> getAttributes concode_elem_sep List<Node> getNodes concode_elem_sep Node createNode concode_elem_sep V getContent concode_elem_sep Node getChild concode_elem_sep R createRelation concode_elem_sep V copyValue concode_elem_sep Collection<Node> getChildren concode_elem_sep Set<Node> getDescendants concode_elem_sep void addAttribute concode_elem_sep int hashCode concode_elem_sep int hashCode concode_elem_sep boolean equals concode_elem_sep boolean equals concode_elem_sep Node merge concode_elem_sep V createValue concode_elem_sep boolean isRelational concode_elem_sep Set<R> getRelations concode_elem_sep String toString concode_elem_sep String toString concode_elem_sep Node copy concode_elem_sep void addChild
target: List < Node > function ( ) { return roots ; }