1module AAA
 2  def aaa
 3    puts "aaa"
 4  end
 5
 6  def self.bbb
 7    puts "bbb"
 8  end
 9end
10
11class C1
12  include AAA
13end
14
15# C1.bbb  # undefined method `bbb' for C1:Class
16# C1.aaa  # undefined method `aaa' for C1:Class
17C1.new.aaa  # aaa
18# C1.new.bbb  # undefined method `bbb' for #<C1:0x007ff1f414af08>
19
20class C2
21  extend AAA
22end
23
24# C2.bbb  # undefined method `bbb' for C2:Class
25C2.aaa  # aaa
26# C2.new.aaa  # undefined method `aaa' for #<C2:0x007f86ea943298>
27# C2.new.bbb  # undefined method `bbb' for #<C2:0x007fc463117270>