Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| No. in series | No. in season | Title | Directed by | Written by | Original air date | Production code | U.S. viewers (million) |
| --- | --- | --- | --- | --- | --- | --- | --- |
| 45.0 | 1.0 | "The Magnificent Seven" | Kim Manners | Eric Kripke | October4,2007 | 3T6901 | 2.97 |
| 46.0 | 2.0 | "The Kids Are Alright" | Phil Sgriccia | Sera Gamble | October11,2007 | 3T6902 | 3.16 |
| 47.0 | 3.0 | "Bad Day at Black Rock" | Robert Singer | Ben Edlund | October18,2007 | 3T6903 | 3.03 |
| 48.0 | 4.0 | "Sin City" | Charles Beeson | Robert Singer & Jeremy Carver | October25,2007 | 3T6904 | 3.02 |
| 49.0 | 5.0 | "Bedtime Stories" | Mike Rohl | Cathryn Humphris | November1,2007 | 3T6905 | 3.24 |
| 50.0 | 6.0 | "Red Sky at Morning" | Cliff Bole | Laurence Andries | November8,2007 | 3T6906 | 3.01 |
| 51.0 | 7.0 | " Fresh Blood " | Kim Manners | Sera Gamble | November15,2007 | 3T6907 | 2.88 |
| 52.0 | 8.0 | " A Very Supernatural Christmas " | J. Miller Tobin | Jeremy Carver | December13,2007 | 3T6908 | 3.02 |
| 53.0 | 9.0 | "Malleus Maleficarum" | Robert Singer | Ben Edlund | January31,2008 | 3T6909 | 2.95 |
| 56.0 | 12.0 | "Jus in Bello" | Phil Sgriccia | Sera Gamble | February21,2008 | 3T6911 | 3.23 |
| 57.0 | 13.0 | "Ghostfacers" | Phil Sgriccia | Ben Edlund | April24,2008 | 3T6913 | 2.22 |
| 58.0 | 14.0 | "Long Distance Call" | Robert Singer | Jeremy Carver | May1,2008 | 3T6914 | 2.63 |
| 59.0 | 15.0 | "Time Is on My Side" | Charles Beeson | Sera Gamble | May8,2008 | 3T6915 | 2.55 |
Question:
Who wrote the last episode (episode 15) of season 3?
Answer:
Sera Gamble