(self, meta_model)
:meta_model is a django model used to store meta info
            must contain columns identifier, filename, length
:meta_model is a django model used to store meta info
            must contain columns identifier, filename, length
: meta_model is a django model used to store meta info must contain columns identifier filename length
def __init__(self, meta_model):
        """
        :meta_model is a django model used to store meta info
            must contain columns identifier, filename, length
        """
        self._meta_model = meta_model
def __init__ ( self , meta_model ) : self . _meta_model = meta_model