e2.py

In [35]: class NF(yaml.YAMLObject):
    yaml_tag=u'tag:yaml.org,2002:nf'
    def __init__(self):
        pass
   ....:

In [36]: class Softnic(yaml.YAMLObject):
    yaml_tag=u'tag:yaml.org,2002:softnic'
    def __init__(self):
        pass
   ....:

In [37]: x = yaml.load(a)

In [38]: x['requests'][0].argument
Out[38]: {'cores': [0]}

In [39]: x['requests'][1].argument
Out[39]: {'arguments': ['-e'], 'cores': [1], 'name': 'firewall', 'nfid': 1}