When ordinary variables cannot be solved by context nodes, a multiplexor (in a slightly different meaning: this time it is to switch to/from default distribution depending on the distribution of the context node) should be used. However, the multiplexor is only being activated when the context node has the form of y=Function(x).
It should also work for other formats.
Namely, it should work with context nodes using predicates (e.g. context nodes using boolean resident nodes), like "Predicate(x,y)".
This seems to be related with #169 as well (because #169 indicates that we cannot have 2 or more context nodes to invoke the multiplexor)
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