def create_variable(var_name)
      ::Sass::Script::Tree::Variable.new(var_name).tap do |v|
        v.line = line # Use line number of the containing parse tree node
      end
    end
def create_variable(var_name)
      ::Sass::Script::Tree::Variable.new(var_name).tap do |v|
        v.line = line # Use line number of the containing parse tree node
      end
    end
Sometimes the parse tree doesn't return a Sass::Script::Variable, but just
 the name of the variable. This helper takes that name and turns it back
 into a Sass::Script::Variable that supports lint reporting.