def raise_unless_all_named_parsers_exist!
      config.columns_with_named_parsers.each do |name, options|
        parser = options[:parser]
        next if named_parsers.include? parser

        raise UnknownParserError.new(name, parser, named_parsers)
      end
    end
def raise_unless_all_named_parsers_exist!
      config.columns_with_named_parsers.each do |name, options|
        parser = options[:parser]
        next if named_parsers.include? parser

        raise UnknownParserError.new(name, parser, named_parsers)
      end
    end
This error has to be raised at runtime because, when the class body
 is being executed, the parser methods won't be available unless
 they are defined above the column definitions in the class body