module Sass::CalculationValue

def assert_calculation_value(value, name = nil)
  if !value.is_a?(Sass::CalculationValue) || (value.is_a?(Sass::Value::String) && value.quoted?)
    raise Sass::ScriptError.new(
      "#{value} must be one of SassNumber, unquoted SassString, SassCalculation, CalculationOperation", name
    )
  end
  value
end