Create placeholders automatically

[BlackHC]

Based on #3

[codecov-io]

Codecov Report

Merging #7 (ec0f60f) into master (6faec75) will decrease coverage by 8.60%.
The diff coverage is 88.88%.

@@             Coverage Diff             @@
##            master       #7      +/-   ##
===========================================
- Coverage   100.00%   91.39%   -8.61%     
===========================================
  Files            1        1              
  Lines           38       93      +55     
===========================================
+ Hits            38       85      +47     
- Misses           0        8       +8     

Impacted Files	Coverage Δ
tfpyth/__init__.py	91.39% <88.88%> (-8.61%)	⬇️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 6faec75...ec0f60f. Read the comment docs.