def get_ss(ss_string):
    """
    Converts secondary structure string into a list of indices of where secondary structure changes (plus start and end coordinates of the sequence)
    """
    output = [0]
    for i in range(1,len(ss_string)):
        if ss_string[i] != ss_string[i-1]:
            output.append(i)
    if output[-1] != len(ss_string)-1:
        output.append(len(ss_string)-1)
    return output