def getNtColours():
    """
    Generates a dictionary which assigns a colour to each nucleotide (plus grey
    for "N" and white for "-")
    Parameters
    ----------
    None

    Returns
    -------
    dict
        Dictionary where keys are single letter nucleotide codes and
        values are hexadecimal codes for colours
    """
    return {'A': '#1ed30f', 'G': '#f4d931', 'T': '#f43131', 'C': '#315af4',
        'N': '#b2b2b2', '-': '#FFFFFF', 'U': '#f43131', 'R': '#b2b2b2', 'Y':
        '#b2b2b2', 'S': '#b2b2b2', 'W': '#b2b2b2', 'K': '#b2b2b2', 'M':
        '#b2b2b2', 'B': '#b2b2b2', 'D': '#b2b2b2', 'H': '#b2b2b2', 'V':
        '#b2b2b2', 'X': '#b2b2b2'}
