fixed issue #325

[tkoyama010]

fixed issue #325

[codecov-io]

Codecov Report

Merging #822 into master will decrease coverage by <.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #822      +/-   ##
==========================================
- Coverage   50.86%   50.85%   -0.01%     
==========================================
  Files         263      263              
  Lines       23846    23846              
  Branches     3252     3252              
==========================================
- Hits        12130    12128       -2     
- Misses      10929    10931       +2     
  Partials      787      787

Impacted Files	Coverage Δ
tvtk/tvtk_base.py	78.96% <0%> (-0.86%)	⬇️
tvtk/wrapper_gen.py	10.96% <0%> (ø)	⬆️

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[prabhuramachandran]

Thank you!

[tkoyama010]

Thank you!