def validates_to_be_string_or_symbol!(value)
      case
      when value.nil?, value == "", value == :""
        raise ArgumentError, "#{value} is empty string or symbol"
      when !value.is_a?(String) && !value.is_a?(Symbol)
        raise ArgumentError, "#{value} is not string or symbol"
      else
        true
      end
    end
def validates_to_be_string_or_symbol!(value)
      case
      when value.nil?, value == "", value == :""
        raise ArgumentError, "#{value} is empty string or symbol"
      when !value.is_a?(String) && !value.is_a?(Symbol)
        raise ArgumentError, "#{value} is not string or symbol"
      else
        true
      end
    end
文字列またはシンボルでないとエラー