class Numeric
  @@currencies = {'dollar' => 1, 'yen' => 0.013, 'euro' => 1.292, 'rupee' => 0.019}
  def method_missing(method_id)
    singular_currency = method_id.to_s.gsub( /s$/, '')
    if @@currencies.has_key?(singular_currency)
      self * @@currencies[singular_currency]
    else
      super
    end
end

  def in(cur)
    singular_currency = cur.to_s.gsub(/s$/, '')
    self / @@currencies[singular_currency]
  end

end


def add_method(c, m, &b)
  c.class_eval {
    define_method(m, &b)
  }
end

add_method(String, :palindrome?) { self.to_s.gsub(/([-.,\s'!:~?])/, '').reverse.downcase == self.to_s.gsub(/([-.,\s'!~:?])/, '').downcase }


module Enumerable
  def palindrome?
    if self.is_a?(Hash)
      false
    else
      self.to_a.join('').gsub(/([-.,\s'!:~?])/, '').reverse.downcase == self.to_a.join('').gsub(/([-.,\s'!~:?])/, '').downcase
    end
  end
end


puts (1..1).palindrome?
puts "fooof".palindrome?
puts ['1', '2', '1'].palindrome?