     end
   end
 
+  % Returns true if integer
   def integer?
     Erlang.is_integer self
   end
 
+  % Returns true if zero
   def zero?
     self == 0
   end
 
+  % Returns true if not zero
   def nonzero?
     !zero?
   end

    round
  end

  def floor
    case self
    match x when x < 0 then (x - 1).truncate

module Numeric

  % Returns the absolute value of self.
  def abs
    Erlang.abs(self)
  end

  % Returns square of self.
  def abs2
    self * self
  end
