def render_header
      return unless requires_header?

      if IOStreams.blank?(header.columns)
        raise(Errors::MissingHeader, "Header columns must be set before attempting to render a header for format: #{format.inspect}")
      end

      parser.render(header.columns, header)
    end
def render_header
      return unless requires_header?

      if IOStreams.blank?(header.columns)
        raise(Errors::MissingHeader, "Header columns must be set before attempting to render a header for format: #{format.inspect}")
      end

      parser.render(header.columns, header)
    end
Returns [String] the header rendered for the output format
 Return nil if no header is required.