Merges copies of value1 and value2. Values that are not
of type GST_TYPE_LIST are treated as if they were lists of length 1.
The result will be put into dest and will either be a list that will not
contain any duplicates, or a non-list type (if value1 and value2
were equal).
Merges copies of value1 and value2. Values that are not of type GST_TYPE_LIST are treated as if they were lists of length 1. The result will be put into dest and will either be a list that will not contain any duplicates, or a non-list type (if value1 and value2 were equal).