Address Rubocop style issues #14

Job	Run time
specs (ubuntu, 3.0.6)	1m 32s
RuboCop	24s
specs (ubuntu, 3.1.4)	1m 32s
specs (ubuntu, 3.2.2)	1m 23s
specs (ubuntu, 3.3.0)	1m 22s
specs (macos, 3.0.6)	1m 40s
specs (macos, 3.1.4)	1m 23s
specs (macos, 3.2.2)	1m 10s
specs (macos, 3.3.0)	1m 25s
specs (windows, 3.0.6)	6m 28s
specs (windows, 3.1.4)	6m 26s
specs (windows, 3.2.2)	6m 25s
specs (windows, 3.3.0)	7m 33s
specs (ubuntu, 3.3.0, --enable-frozen-string-literal)	1m 23s
	40m 6s

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