Don't alter the method parameter

method_missing_fun.rb

class Car

  # http://ruby-doc.org/docs/ProgrammingRuby/html/ref_c_object.html#Object.method_missing
  def method_missing(method, *args, &block)
    # don't do:
    method.gsub!("gasoline", "electricity")
    # also don't do:
    method = method.to_s
    # ...
    super
  end

end