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vs_random(+VS, -X)
Retrieve a random variable from a varset
- VS
- A varset
- X
- Tentative variable (output)
Description
	Retrieve a random variable from a varset.
    
Modes and Determinism
- vs_random(+, -) is semidet
Examples
    ?- Vars=[A,B,C], tent_set(Vars, [a,b,c]), vs_create(Vars, VS),
       vs_random(VS, Var).
    Vars = [Var{a -> 0}, B{b -> 0}, C{c -> 0}]
    VS = ...
    Var = Var{a -> 0}	% A, B or C, the result is random!
    Yes (0.00s cpu)
    
See Also
vs_create / 2, vs_element / 3, vs_random_index / 2