def METHOD_NAME(net):
    # Here the possible new lines are a copy of all the lines which are already in the grid
    max_idx = max(net["line"].index)
    net["line"] = pd.concat([net["line"]] * 2, ignore_index=True) # duplicate
    # they must be set out of service in the line DataFrame (otherwise they are already "built")
    net["line"].loc[max_idx + 1:, "in_service"] = False
    # get the index of the new lines
    new_lines = net["line"].loc[max_idx + 1:].index
    # creates the new line DataFrame net["ne_line"] which defines the measures to choose from. The costs are defined
    # exemplary as 1. for every line.
    init_ne_line(net, new_lines, construction_costs=np.ones(len(new_lines)))
    return net