 module Numeric
 
+  % Returns the absolute value of self.
   def abs
     Erlang.abs(self)
   end
 
+  % Returns square of self.
   def abs2
     self * self
   end

    end
  end

  def integer?
    Erlang.is_integer self
  end

  def zero?
    self == 0
  end

  def nonzero?
    !zero?
  end

    round
  end

  % Returns the largest Integer less than or equal to self.
  def floor
    case self
    match x when x < 0 then (x - 1).truncate
