Ubuntu16.04 报错ImportError: torch.utils.ffi requires the cffi package

Traceback (most recent call last):
File “/home/warp-ctc/pytorch_binding/setup.py”, line 7, in
from torch.utils.ffi import create_extension
File “/usr/local/lib/python2.7/dist-packages/torch/utils/ffi/init.py”, line 15, in
raise ImportError(“torch.utils.ffi requires the cffi package”)
ImportError: torch.utils.ffi requires the cffi package