Well, you could use Loader=yaml.BaseLoader
to leave everything as a string:
>>> x = [[1,2,3], {1:2}]
>>> s = yaml.dump(x)
>>> s
'- [1, 2, 3]\n- {1: 2}\n'
>>> yaml.load(s)
[[1, 2, 3], {1: 2}]
>>> yaml.load(s, Loader=yaml.BaseLoader)
[[u'1', u'2', u'3'], {u'1': u'2'}]