(self, key)
Check if blob exists

        :param key: Blob key.
        :returns: True if the object exists else false.
Check if blob exists
Check if blob exists
def exists(self, key):
        """Check if blob exists

        :param key: Blob key.
        :returns: True if the object exists else false.
        """
        raise NotImplementedError
def exists ( self , key ) : raise NotImplementedError