'Return the set of sequences for the folder.'

def getsequences(self):

    sequences = {}
    fullname = self.getsequencesfilename()
    try:
        f = open(fullname, 'r')
    except IOError:
        return sequences
    while 1:
        line = f.readline()
        if (not line):
            break
        fields = line.split(':')
        if (len(fields) != 2):
            self.error(('bad    sequence    in    %s:    %s' % (fullname, line.strip())))
        key = fields[0].strip()
        value = IntSet(fields[1].strip(), '    ').tolist()
        sequences[key] = value
    return sequences
