Attempt to ignore some cells with nbsphinx extra arguments.

Author: jasongrout

docs/source/conf.py

@@ -57,6 +57,8 @@
 
 nbsphinx_execute = 'always'
 
+nbsphinx_execute_arguments = ['''--RegexRemovePreprocessor.patterns="['widget']" --RegexRemovePreprocessor.enabled=True''']
+
 # -- General information -------
 
 _release = {}