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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 _describe_atom(topology, index):
 """ Returns a string describing the given atom :param topology: :param index: :return: """

    at = topology.atom(index)
    if topology.n_chains > 1:
        return "%s %i %s %i %i" % (at.residue.name, at.residue.resSeq, at.name, at.index, at.residue.chain.index )
    else:
        return "%s %i %s %i"    % (at.residue.name, at.residue.resSeq, at.name, at.index)