Support required options

[BMBurstein]

[codecov[bot]]

Codecov Report

Merging #28 into master will increase coverage by 1.84%. The diff coverage is 93.93%.

@@            Coverage Diff             @@
##           master      #28      +/-   ##
==========================================
+ Coverage   93.38%   95.23%   +1.84%     
==========================================
  Files           2        2              
  Lines         680      713      +33     
==========================================
+ Hits          635      679      +44     
+ Misses         45       34      -11

Impacted Files	Coverage Δ
include/clara.hpp	94.45% <93.93%> (+2.61%)	:arrow_up:

---

Continue to review full report at Codecov.

Legend - Click here to learn more Δ = absolute <relative> (impact), ø = not affected, ? = missing data Powered by Codecov. Last update ce73a42...d9032af. Read the comment docs.