internal OrderByClause(WhereClause whereClause, IReadOnlyList<string> orderings)
 {
     this.whereClause = whereClause;
     this.orderings = orderings;
 }
 internal OrderByClause(WhereClause whereClause, IReadOnlyList <string> orderings)
 {
     this.whereClause = whereClause;
     this.orderings   = orderings;
 }