Function listUnion() merges, deduplicates, and returns all the elements of two arrays as a new array, namely, returns the union of these two arrays (repeated elements are NOT allowed in the union).
Arguments：
- 1st array <array>
- 2nd array <array>
Returns：
- Union <array>
If the two arrays are non-homologous, Cartesian Product will be applied when the function is called in a WITH clause, or aliases will be trimmed when called in a RETURN clause.
Common Usage
Example: Find all the neighbors of Card CA001 and CA002, deduplicate them and return as array
khop().src({_id == "CA001"}).depth(1) as n1
khop().src({_id == "CA002"}).depth(1) as n2
with collect(n1) as a1, collect(n2) as a2
return listUnion(a1, a2)