# File lib/sass/tree/visitors/cssize.rb, line 125
  def visit_mixin(node)
    # Don't use #visit_children to avoid adding the mixin node to the list of parents.
    node.children.map {|c| visit(c)}.flatten
  rescue Sass::SyntaxError => e
    e.modify_backtrace(:mixin => node.name, :filename => node.filename, :line => node.line)
    e.add_backtrace(:filename => node.filename, :line => node.line)
    raise e
  end