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<pre><code class="python">def fixed_rspace_nodes(L,primes):
    &#34;&#34;&#34;Finds the nodes that must have a fixed value in order for the rspace
    constraint L to be satisfied in the system given by primes.


    Parameters
    ----------
    L : rspace list
        Restrict space list (see restrict_space.rspace for details).
    primes : pyboolnet primes dictionary
        Update rule for the system.

    Returns
    -------
    dictionary
        Nodes th