def filter_on_cdr3_bounding_aas(df):
    """
    Only take sequences that have a C at the beginning and a F or a YV at the
    end of the `amino_acid` column.

    Note that according to the Adaptive docs the `amino_acid` column is indeed
    the CDR3 amino acid.
    """
    return df[df['amino_acid'].str.contains('^C.*F$') | df['amino_acid'].str.contains('^C.*YV$')]