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. | # | Title | Directed by | Written by | U.S. viewers (million) | Rank (week) | Original air date | Production code |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 48.0 | 1.0 | "Sacrifice" | David Mamet | Frank Military | 9.71 (repeat: 3.9 on February 1 , 2009 at 9pm) | 29 | September28,2008 | 4ALF01 |
| 49.0 | 2.0 | "Sudden Flight" | Steven DePaul | Sharon Lee Watson | 9.46 (repeat: 5.5 million on February 22 , 2009) | 26 | October5,2008 | 4ALF02 |
| 50.0 | 3.0 | "Sex Trade" | Jesús Salvador Treviño | Todd Ellis Kessler | 9.10 | 29 | October12,2008 | 4ALF03 |
| 51.0 | 4.0 | " The Conduit " | Michael Zinberg | David Mamet | 8.28 | 36 | October19,2008 | 4ALF04 |
| 52.0 | 5.0 | "Dancing Lessons" | Steve Gomer | Lynn Mamet & Ted Humphrey | 9.17 | 36 | October26,2008 | 4ALF05 |
| 53.0 | 6.0 | "Inquisition" | David Paymer | Patrick Moss & Shannon Rutherford | 8.98 | 40 | November2,2008 | 4ALF06 |
| 54.0 | 7.0 | "Into Hell (Part 1)" | Krishna Rao | Daniel Voll | 9.87 | 27 | November9,2008 | 4ALF07 |
| 55.0 | 8.0 | "Into Hell (Part 2)" | Fred Gerber | Frank Military | 10.23 | 27 | November16,2008 | 4ALF08 |
| 56.0 | 9.0 | "Shadow Riders" | Vahan Moosekian | Sharon Lee Watson | 9.99 | 30 | November23,2008 | 4ALF09 |
| 57.0 | 10.0 | "Misled and Misguided" | Steven DePaul | Todd Ellis Kessler | 9.6 (at 10:30) | N/A | November30,2008 | 4ALF10 |
| 58.0 | 11.0 | "Switchblade" | Oz Scott | David Mamet | 8.2 | N/A | December21,2008 | 4ALF11 |
| 59.0 | 12.0 | " Bad Beat " | Bill L. Norton | Ted Humphrey | 9.7 | N/A | January4,2009 | 4ALF12 |
| 60.0 | 13.0 | "The Spear of Destiny" | Scott Foley | Lynn Mamet & Benjamin Daniel Lobato | 10.16 | 24 | January11,2009 | 4ALF13 |
| 61.0 | 14.0 | "The Last Nazi" | Michael Offer | David Mamet | 8.4 | N/A | February15,2009 | 4ALF14 |
| 62.0 | 15.0 | " Hero " | Terrence O'Hara | R. Scott Gemmill & Randy Huggins | 9.38 | 33 | March8,2009 | 4ALF15 |
| 63.0 | 16.0 | " Hill 60 " | James Whitmore, Jr. | Ted Humphrey | 10.87 | 21 | March15,2009 | 4ALF16 |
| 64.0 | 17.0 | " Flesh & Blood " | Dennis Haysbert | Lynn Mamet & Pete Blaber | 8.14 (at 10:52) | 35 | March22,2009 | 4ALF17 |
| 65.0 | 18.0 | " Best Laid Plans " | Dean White | Benjamin Daniel Lobato & Patrick Moss | 9.5 (at 10:20) | N/A | March29,2009 | 4ALF18 |
| 66.0 | 19.0 | " Whiplash " | Seth Wiley | Dan Hindmarch | 9.05 (at 10:30) | 28 | April12,2009 | 4ALF19 |
| 67.0 | 20.0 | " Chaos Theory " | Gwyneth Horder-Payton | Sharon Lee Watson | 8.8 | N/A | April26,2009 | 4ALF20 |
| 68.0 | 21.0 | " End Game " | Lesli Linka Glatter | Ted Humphrey | 10 | N/A | May3,2009 | 4ALF21 |
Question:
What was the production code of the episode ranked 28?
Answer:
4ALF19