Fix sequencial optional

[zaibacu]

Closes #69

Turns out it is a bug related to - character which in most cases used as a splitter, but in this case as a stand alone word

[codecov]

Codecov Report

Merging #71 into master will increase coverage by 0.02%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master      #71      +/-   ##
==========================================
+ Coverage   93.03%   93.05%   +0.02%     
==========================================
  Files          11       11              
  Lines         617      619       +2     
  Branches      104      105       +1     
==========================================
+ Hits          574      576       +2     
  Misses         29       29              
  Partials       14       14              

Impacted Files	Coverage Δ
rita/preprocess.py	99.24% <100.00%> (+0.01%)	⬆️

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