module X
  def add0()
    return 0
  end
  def add00
    return 0
  end
  def add1(n)
    return n
  end
  def add2(n, m)
    return n + m
  end
  def add3(n = 0, m)
    return n + m
  end
  def add4(n = 0, m = 0)
    return n + m
  end
  def add5(n    =     0    ,    m    =   0)
    return n + m
  end    
  def addm (n = 0,
            m = 0)
    return n + m
  end
end
