title: ModuleNotFoundError: No module named 'pycocotools._mask'
body: <p>I'm trying to train Mask-R CNN model from cocoapi(<a href="https://github.com/cocodataset/cocoapi" rel="nofollow noreferrer">https://github.com/cocodataset/cocoapi</a>), and this error code keep come out.</p>
  <pre><code>    ModuleNotFoundError                       Traceback (most recent call last)
      &lt;ipython-input-8-83356bb9cf95&gt; in &lt;module&gt;
           19 sys.path.append(os.path.join(ROOT_DIR, &quot;samples/coco/&quot;))  # To find local version
           20 
      ---&gt; 21 from pycocotools.coco import coco
           22 
           23 get_ipython().run_line_magic('matplotlib', 'inline ')
  
  ~/Desktop/coco/PythonAPI/pycocotools/coco.py in &lt;module&gt;
       53 import copy
       54 import itertools
  ---&gt; 55 from . import mask as maskUtils
       56 import os
       57 from collections import defaultdict
  
  ~/Desktop/coco/PythonAPI/pycocotools/mask.py in &lt;module&gt;
        1 __author__ = 'tsungyi'
        2 
  ----&gt; 3 import pycocotools._mask as _mask
        4 
        5 # Interface for manipulating masks stored in RLE format.
  
  ModuleNotFoundError: No module named 'pycocotools._mask'
  </code></pre>
  <p>I tried all the methods on the github 'issues' tab, but it is not working to me at all. Is there are another solution for this? I'm using Python 3.6, Linux.</p>