GAP 4.8.9 installation with standard packages -- copy to your CoCalc project to get it
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##
#W id4.z GAP library of id's Hans Ulrich Besche
##
ID_GROUP_TREE.next[4]:=
rec(
fp:= [ 1 ],
next:= [ rec(
fp:= [ 4 ],
next:= [ rec(
fp:= [ 2 ],
next:= [ rec(
fp:= [ 12, 13 ],
next:= [ 19, 20 ] ) ] ) ] ) ] );