user: Question: Can you tell me the total number of Yards per return that has the Player of gizmo williams, and the Games smaller than 13?
Columns: ['Player', 'Games', 'Returns', 'Yards', 'Long', 'Yards per return']
Types: ['text', 'real', 'real', 'real', 'real', 'real']
Sample row: ['Keith Byars', 16.0, 1.0, 27.0, 27.0, 27.0]
SQL:

assistant: SELECT SUM("Yards per return") FROM "Table" WHERE "Player" = 'gizmo williams' AND "Games" < 13.0;