code: func (c Columns) Readable() *ReadableColumns {
  	w := &ReadableColumns{NewColumnsWithAlias(c.TableName, c.TableAlias)}
  	for _, col := range c.Cols {
  		if col.Readable {
  			w.Cols[col.Name] = col
  		}
  	}
  	return w
  }
docs: // Readable gets a list of the readable columns from the column list.