rubocop: fixed "Redundant begin block"
rubocop: fixed "Space missing after comma"
rubocop: fixed "File.exists? is deprecated in favor of File.exist?"
rubocop: fixed "Unused block argument"
rubocop: fixed "Hash#has_key? is deprecated in favor of Hash#key?"
rubocop: fixed "Extra blank line"
rubocop: fixed "Do not use parentheses for method calls with no arguments"
rubocop: fixed "Avoid the use of Perl-style backrefs"
rubocop: fixed "trailing blank lines"
rubocop: fixed "trailing comma"
rubocop: fixed "Pass &:unregistered as an argument to each instead of a block"
rubocop: fixed "Redundant return"
rubocop: fixed "Surrounding space missing for operators"
rubocop: fixed "Incorrect indentation"