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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 concretize_load_idx(self, idx, strategies=None):
 """ Concretizes a load index. :param idx: An expression for the index. :param strategies: A list of concretization strategies (to override the default). :param min_idx: Minimum value for a concretized index (inclusive). :param max_idx: Maximum value for a concretized index (exclusive). :returns: A list of concrete indexes. """

        if isinstance(idx, int):
            return [idx]
        elif not self.state.solver.symbolic(idx):
            return [self.state.solver.eval(idx)]

        strategies = self.load_strategies if strategies is None else strategies
        return self._apply_concretization_strategies(idx, strategies, 'load')