gistfile1.rb

gauss:rubinius brian$ irb
>> module M
>> private
>> def foo
>> puts 'foo'
>> end
>> end
=> nil
>> class F
>> include M
>> def bar
>> puts 'bar'
>> foo
>> end
>> end
=> nil
>> f = f.new
NoMethodError: undefined method `new' for nil:NilClass
        from (irb):14
>> f = F.new
=> #<F:0x5e78b0>
>> f.bar
bar
foo
=> nil
>> f.foo
NoMethodError: private method `foo' called for #<F:0x5e78b0>
        from (irb):17