Return a json representation (str) of this blob.
    Takes the same arguments as json.dumps.
    .. versionadded:: 0.5.1

def to_json(self, *args, **kwargs):
    '''Return a json representation (str) of this blob.
    Takes the same arguments as json.dumps.
    .. versionadded:: 0.5.1
    '''
    try:
      import ujson as json
    except ImportError:
      import json
    return json.dumps(self.serialized, *args, **kwargs)