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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 enrich_proteins_with_rnas(graph):
 """Add the corresponding RNA node for each protein node and connect them with a translation edge. :param pybel.BELGraph graph: A BEL graph """

    for protein_node in list(graph):
        if not isinstance(protein_node, Protein):
            continue

        if protein_node.variants:
            continue

        rna_node = protein_node.get_rna()
        graph.add_translation(rna_node, protein_node)