You will be shown an excerpt from a computer science scientific research paper, followed by a question about the paper. Please answer the question. Do not include any text in your response other than the answer.

Context: 

Question: If MXNet supported only a push mechanism (and no pull mechanism) available for inter-rank communication, would it still be possible to implement an all_reduce primitive on MXNet?
Since there are no evidential information about all_reduce and inter-rank communication, this question cannot be answered and requires external knowledges.