Make sure that reference nucleotides we expect to see on the reference
    transcript from a variant are the same ones we encounter.

def variant_matches_reference_sequence(variant, ref_seq_on_transcript, strand):
    """
    Make sure that reference nucleotides we expect to see on the reference
    transcript from a variant are the same ones we encounter.
    """
    if strand == "-":
        ref_seq_on_transcript = reverse_complement_dna(ref_seq_on_transcript)
    return ref_seq_on_transcript == variant.ref