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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def preProcess(self, variables, domains, constraints, vconstraints):
 """ Preprocess variable domains This method is called before starting to look for solutions, and is used to prune domains with specific constraint logic when possible. For instance, any constraints with a single variable may be applied on all possible values and removed, since they may act on individual values even without further knowledge about other assignments. @param variables: Variables affected by that constraint, in the same order provided by the user @type variables: sequence @param domains: Dictionary mapping variables to their domains @type domains: dict @param constraints: List of pairs of (constraint, variables) @type constraints: list @param vconstraints: Dictionary mapping variables to a list of constraints affecting the given variables. @type vconstraints: dict """

        if len(variables) == 1:
            variable = variables[0]
            domain = domains[variable]
            for value in domain[:]:
                if not self(variables, domains, {variable: value}):
                    domain.remove(value)
            constraints.remove((self, variables))
            vconstraints[variable].remove((self, variables))