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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 _get_label(placeholder, label_mapping, label_i):
 """Helper function to either get the appropriate label for a given placeholder or generate a new label and update the mapping. See :py:func:`instantiate_labels` for usage. """

    if placeholder in label_mapping:
        return label_mapping[placeholder], label_mapping, label_i

    new_target = Label("{}{}".format(placeholder.prefix, label_i))
    label_i += 1
    label_mapping[placeholder] = new_target
    return new_target, label_mapping, label_i