Array/grep_vs_include?.rb Blocks/implicit_block-vs-explicit_block.rb Blocks/yield_if-vs-block_given_amp_amp.rb Hash/has_key-vs-hash[key].rb Integer/integer-vs-to_i.rb Misc/gc-symbol_vs_string.rb Misc/is_a?-vs-threequals.rb Misc/lambdas_vs_class.rb Misc/loop_vs_while.rb String/downcase-eq-eq_vs_casecmp.rb String/string_appender.rb String/string_ranged_index.rb String/to_s-vs-String_paren.rb