class Sass::Script::Tree::Interpolation

def _perform(environment)
  res = ""
  res << @before.perform(environment).to_s if @before
  res << " " if @before && @whitespace_before
  val = @mid.perform(environment)
  if @warn_for_color && val.is_a?(Sass::Script::Value::Color) && val.name
    alternative = Operation.new(Sass::Script::Value::String.new("", :string), @mid, :plus)
    Sass::Util.sass_warn <<MESSAGE
ING on line #{line}, column #{source_range.start_pos.offset}#{" of #{filename}" if filename}:
probably don't mean to use the color value `#{val}' in interpolation here.
ay end up represented as #{val.inspect}, which will likely produce invalid CSS.
ys quote color names when using them as strings (for example, "#{val}").
ou really want to use the color value here, use `#{alternative.to_sass}'.
AGE
  end
  res << val.to_s(:quote => :none)
  res << " " if @after && @whitespace_after
  res << @after.perform(environment).to_s if @after
  str = Sass::Script::Value::String.new(
    res, :identifier,
    (to_quoted_equivalent.to_sass if deprecation == :potential))
  str.source_range = source_range
  opts(str)
end