Update code style of Coalesce transform

[eliascarv]

Update code style of Coalesce to match with code style of Replace.

[codecov-commenter]

Codecov Report

Merging #45 (2d2785b) into master (edd4c24) will decrease coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master      #45      +/-   ##
==========================================
- Coverage   92.85%   92.84%   -0.02%     
==========================================
  Files          19       19              
  Lines         462      461       -1     
==========================================
- Hits          429      428       -1     
  Misses         33       33              

Impacted Files	Coverage Δ
src/transforms/coalesce.jl	100.00% <100.00%> (ø)

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