orm.go
func (f *Field) SetTimestamp(rowIDOrKey, colIDOrKey interface{}, timestamp time.Time) *PQLBaseQuery {
	rowStr, colStr, err := formatRowColIDKey(rowIDOrKey, colIDOrKey)
	if err != nil {
		return NewPQLBaseQuery("", f.index, err)
	}
	text := fmt.Sprintf("Set(%s,%s=%s,%s)", colStr, f.name, rowStr, timestamp.Format(timeFormat))
	q := NewPQLBaseQuery(text, f.index, nil)
	q.hasKeys = f.options.keys || f.index.options.keys
	return q
}
func (f *Field) SetTimestamp(rowIDOrKey, colIDOrKey interface{}, timestamp time.Time) *PQLBaseQuery {
	rowStr, colStr, err := formatRowColIDKey(rowIDOrKey, colIDOrKey)
	if err != nil {
		return NewPQLBaseQuery("", f.index, err)
	}
	text := fmt.Sprintf("Set(%s,%s=%s,%s)", colStr, f.name, rowStr, timestamp.Format(timeFormat))
	q := NewPQLBaseQuery(text, f.index, nil)
	q.hasKeys = f.options.keys || f.index.options.keys
	return q
}
// SetTimestamp creates a Set query with timestamp.
// Set, assigns a value of 1 to a column in the binary matrix,
// thus associating the given row in the given field with the given column.