feat: implement a helper method for Chinese Mandarian language

[danielotieno]

"fix #19"

Proposed changes

• Add a helper method for Chinese Mandarin language and it's testing.

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Types of changes

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• [ ] Bugfix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [x] Documentation Update (if none of the other choices applies)

Checklist

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• [x] I have read the CONTRIBUTING doc
• [x] Lint and unit tests pass locally with my changes
• [x] I have added tests that prove my fix is effective or that my feature works
• [x] I have added necessary documentation (if appropriate)

[codecov-io]

Codecov Report

Merging #54 into master will not change coverage. The diff coverage is 100%.

@@          Coverage Diff          @@
##           master    #54   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files           1      1           
  Lines          46     49    +3     
  Branches        3      3           
=====================================
+ Hits           46     49    +3

Impacted Files	Coverage Δ
src/index.js	100% <100%> (ø)	:arrow_up:

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[chgasparoto]

I'll wait one more week for the conflict fix otherwise I'm going to close it 😉