8: Return reference to self from matches func to enable chaining

[MrTact]

Fixes #8

• Implementated
• Test added
• Documented

[codecov]

Codecov Report

Merging #9 (f58b7d1) into main (3c7c527) will decrease coverage by 3.23%.
The diff coverage is 85.71%.

❗ Current head f58b7d1 differs from pull request most recent head 28820aa. Consider uploading reports for the commit 28820aa to get more accurate results

@@            Coverage Diff             @@
##             main       #9      +/-   ##
==========================================
- Coverage   96.76%   93.53%   -3.24%     
==========================================
  Files          10       10              
  Lines        1856     1067     -789     
==========================================
- Hits         1796      998     -798     
- Misses         60       69       +9     

Impacted Files	Coverage Δ
src/lib.rs	91.13% <85.71%> (-7.42%)	⬇️
src/hashmap.rs	91.50% <0.00%> (-8.50%)	⬇️
src/numeric.rs	93.61% <0.00%> (-6.39%)	⬇️
src/vec.rs	60.78% <0.00%> (-4.65%)	⬇️
src/option.rs	96.36% <0.00%> (-3.64%)	⬇️
src/string.rs	97.77% <0.00%> (-2.23%)	⬇️
src/result.rs	100.00% <0.00%> (ø)
src/boolean.rs	100.00% <0.00%> (ø)
src/iter.rs	94.35% <0.00%> (+0.22%)	⬆️
... and 1 more

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[oknozor]

@MrTact thanks for the addition, I think this would fit with #6 .
Maybe we could add a SofSpec struct for this use case to check all match case before returning a global report.

[MrTact]

Will take a look at that. There's no rush, as I have to fix the code coverage before this PR can be merged anyway.