code: func (f *fragment) rangeOp(op pql.Token, bitDepth uint, predicate uint64) (*Row, error) {
  	switch op {
  	case pql.EQ:
  		return f.rangeEQ(bitDepth, predicate)
  	case pql.NEQ:
  		return f.rangeNEQ(bitDepth, predicate)
  	case pql.LT, pql.LTE:
  		return f.rangeLT(bitDepth, predicate, op == pql.LTE)
  	case pql.GT, pql.GTE:
  		return f.rangeGT(bitDepth, predicate, op == pql.GTE)
  	default:
  		return nil, ErrInvalidRangeOperation
  	}
  }
docs: // rangeOp returns bitmaps with a bsiGroup value encoding matching the predicate.