Prefer square brackets to parentheses as %w delimiters

Introduced in b783cd1ef7af240fcae425c71643a77e39f26a8a.
Use the lambda method for multi-line lambdas
Avoid using {...} for multi-line blocks
Use def with parentheses when there are arguments
Replace explicit lambdas with blocks
Use smaller random numbers
Fix indentation
Prefer the use of the nil? predicate
Name reduce block arguments |a, e| (accumulator, element)
Always use hash rockets in hashes
Use %r for regular expressions matching more than 1 '/' character
Perfer format to String#%
Favor unless (or control flow or) over if for negative conditions
Surrounding space missing in default value assignment
Do not use semicolons to terminate expressions
Provide an exception class and message as arguments to fail
Use space after control keywords
Use alias_method instead of alias
Use ! instead of not
has_key? is deprecated in favor of key?