code: func (s *CatAllocationService) Columns(columns ...string) *CatAllocationService {
  	s.columns = columns
  	return s
  }
docs: // Columns to return in the response.
  // To get a list of all possible columns to return, run the following command
  // in your terminal:
  //
  // Example:
  //   curl 'http://localhost:9200/_cat/aliases?help'
  //
  // You can use Columns("*") to return all possible columns. That might take
  // a little longer than the default set of columns.