class RuboCop::Cop::Layout::Tab

def string_literal_ranges(ast)
  # which lines start inside a string literal?
  return [] if ast.nil?
  ast.each_node(:str, :dstr).each_with_object(Set.new) do |str, ranges|
    loc = str.location
    range = if str.heredoc?
              loc.heredoc_body
            else
              loc.expression
            end
    ranges << range
  end
end