Understand What Ruby considers to be True ref: http://qiita.com/giwa/items/8d083c48152bdb99f3fa

file0.rb

[3] pry(main)> true.class
=> TrueClass
[4] pry(main)> false.class
=> FalseClass

file1.txt

if false == x
 ...
end

file2.rb

[5] pry(main)> class Bad
[5] pry(main)*   def == (other)
[5] pry(main)*     true
[5] pry(main)*   end
[5] pry(main)* end
=> :==
[6] pry(main)> false == Bad.new
=> false
[7] pry(main)> Bad.new == false
=> true

file3.txt

[14] pry(main)> if 0
[14] pry(main)*   p 'I am TRUE'
[14] pry(main)* end
"I am TRUE"
=> "I am TRUE"

file4.txt

[13] pry(main)> nil.nil?
=> true