def check_min_guide_pairs(df, min_pairs):
    """Check that each guide is paired with a minimum number of guides

    Parameters
    ----------
    df: DataFrame
        Anchor df with column anchor_guide
    min_pairs: int
        minimum number of guides to be paired with

    Returns
    -------
    List
        guides that are not paired fewer than min_pairs number of guides
    """
    pair_count = (df[['anchor_guide', 'target_guide']]
                  .drop_duplicates()
                  .groupby('anchor_guide')
                  .apply(lambda d: d.shape[0])
                  .reset_index(name='n'))
    guides_no_pairs = pair_count.anchor_guide[~(pair_count.n >= min_pairs)].to_list()
    return guides_no_pairs