class Monkey2 < Monkey 
 def method2 
  puts "This is method2" 
 end 
  
 alias output method2 
end 
 
monkey = Monkey2.new 
monkey.method2 
monkey.output 

module Helper 
 def help 
  puts "Help..." 
 end 
  
 def method1 
  puts "helper method1..." 
 end 
end 
 
class Monkey 
 include Helper 
 def method1 
  puts "monkey method1..." 
 end 
end 
 
monkey = Monkey.new 
monkey.help 
monkey.method1#因为重名，当前类的方法优先 

class Monkey 
 def method1 
  puts "This is method1" 
 end 
end  
 
class Monkey2 < Monkey 
 def method2 
  puts "This is method2" 
 end 
end 
 
monkey = Monkey2.new 
monkey.method1  
monkey.method2 
 
class Monkey2 
 undef method1 
 undef method2 
end 
 
monkey.method1 
monkey.method2 

class Monkey2 
 remove_method :method1 
 undef_method :method2 
nd