def indent_string(string, *args)
      string = string.dup
      indent_string!(string, *args)
      string
    end
def indent_string(string, *args)
      string = string.dup
      indent_string!(string, *args)
      string
    end
Same as #indent from active-support
 https://github.com/rails/rails/blob/10e1f1f9a129f2f197a44009a99b73b8ff9dbc0d/activesupport/lib/active_support/core_ext/string/indent.rb#L42