Ruby Palindrome String

string.rb

class String 
  def palindrome?
    clean_string = self.gsub(/[^\w]/, '').downcase
    clean_string == clean_string.reverse
  end
end
puts "madam".palindrome?     # => true
puts "racecar".palindrome?   # => true
puts "madam, . ".palindrome? # => true
puts "02/02/2020".palindrome?     # => true
puts "11/11/11 11:11".palindrome? # => true
puts "Madam, I'm Adam".palindrome?                 # => true
puts "A man, a plan, a canal – Panama".palindrome? # => true