Issue 566a

[jverzani]

Address last example given in #566.

• better handles rational function of Laurent polynomials
• needed to make promote_rule promote to Laurent type, not Polynomial type.

[codecov]

Codecov Report

Attention: Patch coverage is 92.59259% with 2 lines in your changes are missing coverage. Please review.

Project coverage is 75.69%. Comparing base (263b965) to head (55a58f8).

Files	Patch %	Lines
src/rational-functions/rational-function.jl	92.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #570      +/-   ##
==========================================
- Coverage   75.79%   75.69%   -0.10%     
==========================================
  Files          38       38              
  Lines        4032     4037       +5     
==========================================
  Hits         3056     3056              
- Misses        976      981       +5     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.