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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 build_vf_node(vf):
 """ Convert a VulnerabilityFunction object into a Node suitable for XML conversion. """

    nodes = [Node('imls', {'imt': vf.imt}, vf.imls),
             Node('meanLRs', {}, vf.mean_loss_ratios),
             Node('covLRs', {}, vf.covs)]
    return Node(
        'vulnerabilityFunction',
        {'id': vf.id, 'dist': vf.distribution_name}, nodes=nodes)