def _copy_rows(data, num_rows, base_row_index=0):
    """
    Copies one list from a list of lists and adds it to the same list n times.

    Parameters
    ----------
    data: [][]
        Dataset to apply the function to. This will be mutated.
    base_row_index: int
        The index of the row to copy
    num_rows: int
        The number of times to copy the base row.

    Returns
    -------
    [][]
        List of lists, containing the additional copied data.
    """
    copies = [data[base_row_index] for _ in range(num_rows)]
    return data + copies