class TrueClass

# File activesupport/lib/active_support/core_ext/object/blank.rb, line 74
def blank?
  false
end

true не пусто:

true.blank? # => false

@return [false]

# File activesupport/lib/active_support/core_ext/object/duplicable.rb, line 68
def duplicable?
  false
end

true не дублируемый:

true.duplicable? # => false
true.dup         # => TypeError: can't dup TrueClass

# File activesupport/lib/active_support/core_ext/object/to_query.rb, line 25
def to_param
  self
end

Возвращает self.