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method_defined? 

        # Module.method_defined?

(from ruby core)
---
    mod.method_defined?(symbol, inherit=true)    -> true or false
    mod.method_defined?(string, inherit=true)    -> true or false

---

Returns `true` if the named method is defined by *mod*.  If *inherit* is
set, the lookup will also search *mod*'s ancestors. Public and protected
methods are matched. String arguments are converted to symbols.

    module A
      def method1()  end
      def protected_method1()  end
      protected :protected_method1
    end
    class B
      def method2()  end
      def private_method2()  end
      private :private_method2
    end
    class C < B
      include A
      def method3()  end
    end

    A.method_defined? :method1              #=> true
    C.method_defined? "method1"             #=> true
    C.method_defined? "method2"             #=> true
    C.method_defined? "method2", true       #=> true
    C.method_defined? "method2", false      #=> false
    C.method_defined? "method3"             #=> true
    C.method_defined? "protected_method1"   #=> true
    C.method_defined? "method4"             #=> false
    C.method_defined? "private_method2"     #=> false

This is MURDOC! A Ruby documentation browser inspired by Smalltalk-80. It allows you to learn about Ruby by browsing through its class hierarchies, and see any of its methods.