element.rb

module Element
  alias_method :near_equal?, :===

  def ===(other)
    other.respond_to?(:include?) ? other.include?(self) : self.near_equal?(other)
  end
end

[String, Symbol, Numeric].each do |elm|
  elm.send(:include, Element)
end

case %w(a b c)
when 'a'
  puts 'A'
else
  puts '>_<'
end # => A