code: func (builder *RequestBuilder) SetIndexRanges(sc *stmtctx.StatementContext, tid, idxID int64, ranges []*ranger.Range) *RequestBuilder {
  	if builder.err != nil {
  		return builder
  	}
  	builder.Request.KeyRanges, builder.err = IndexRangesToKVRanges(sc, tid, idxID, ranges, nil)
  	return builder
  }
docs: // SetIndexRanges sets "KeyRanges" for "kv.Request" by converting index range
  // "ranges" to "KeyRanges" firstly.