parse ggKbase scaffold-to-bin mapping
        - scaffolds-to-bins and bins-to-scaffolds

def parse_s2bins(s2bins):
    """
    parse ggKbase scaffold-to-bin mapping
        - scaffolds-to-bins and bins-to-scaffolds
    """
    s2b = {}
    b2s = {}
    for line in s2bins:
        line = line.strip().split()
        s, b = line[0], line[1]
        if 'UNK' in b:
            continue
        if len(line) > 2:
            g = ' '.join(line[2:])
        else:
            g = 'n/a'
        b = '%s\t%s' % (b, g)
        s2b[s] = b 
        if b not in b2s:
           b2s[b] = []
        b2s[b].append(s)
    return s2b, b2s