parse [16,23]SfromHMM.py output
    - rna_cov[scaffold] = [0, 0, []] # [bases, length, ranges]

def parse_rna(rna, s2bins, min_rna):
    """
    parse [16,23]SfromHMM.py output
    - rna_cov[scaffold] = [0, 0, []] # [bases, length, ranges]
    """
    rna_cov = {}
    for seq in parse_fasta(rna):
        # check that length passes threshold
        length = len(seq[1])
        if length < min_rna:
            continue
        # check if sequence is binnned
        s = seq[0].split('>')[1].split()[0]
        if s not in s2bins:
            continue
        if s not in rna_cov:
            rna_cov[s] = [0, 0, []]
        position = [int(i) for i in seq[0].rsplit('pos=', 1)[1].split()[0].split('-')]
        rna_cov[s][2].append(position)
        rna_cov[s][1] += length
    return rna_cov