class SassC::Script::Value::Number

def compute_units(this, other, operation)
  case operation
  when :*
    [this.numerator_units + other.numerator_units,
     this.denominator_units + other.denominator_units]
  when :/
    [this.numerator_units + other.denominator_units,
     this.denominator_units + other.numerator_units]
  else
    [this.numerator_units, this.denominator_units]
  end
end