title: Passing nested lists as tensors in tensor flow , where the inner lists have variable lengths
body: <p>I have a list of lists which I want to convert to a tensor and use that in my program. The tricky part being, the inner lists can have variable size. For instance consider the following list- 
  [[[1, 2, 3], [4, 5, 6]], [ [2, 3], [4, 6] ], [[0], [1] ]] .
  So is there a way I can represent this as a tensor and use it in my program(without padding zeros and making lists of same size)? Also I want to pass this as a placeholder.</p>