class Person
  attr_accessor :name
  
  #alias for readability joy  
  alias knows? respond_to?
  
  def initialize(name)
    @name = name
  end
  
  def action(out)
    puts "*#{name} #{out}*"
  end
  
  def say(out)
    puts "#{name}:  #{out}"
  end
  
  def assert_knowledge(method)
    say 'I ' + ( self.knows?(method) ? 'know ' : 'don\'t know ' ) + method.to_s + '. '
  end
end

class MartialArtsLearningTape
  def teach(person)
    
    def person.kung_fu
      # ...
      action 'KA-POW\'z!'
    end
    
    def person.ju_jitsu
      # ...
      action 'HI-YA\'s!'
    end
    
    # ...
  end
end

keanu = Person.new('Thomas Anderson')
keanu.assert_knowledge(:kung_fu)

keanu.action "gets unplugged from the martix"
keanu.name = 'Neo'
MartialArtsLearningTape.new.teach(keanu)

keanu.assert_knowledge(:kung_fu)

laurence = Person.new('Morpheus')
laurence.say 'Show me. '

keanu.say "self.methods.grep(/kung_fu/)\n=> #{keanu.methods.grep(/kung_fu/)}"
laurence.say 'uh....'

keanu.kung_fu