Who wrote the last episode (episode 15) of season 3?
{'header': ['No. in series', 'No. in season', 'Title', 'Directed by', 'Written by', 'Original air date', 'Production code', 'U.S. viewers (million)'], 'page_title': '', 'section_title': '', 'caption': '', 'rows': [['45', '1', '"The Magnificent Seven"', 'Kim Manners', 'Eric Kripke', 'October4,2007', '3T6901', '2.97'], ['46', '2', '"The Kids Are Alright"', 'Phil Sgriccia', 'Sera Gamble', 'October11,2007', '3T6902', '3.16'], ['47', '3', '"Bad Day at Black Rock"', 'Robert Singer', 'Ben Edlund', 'October18,2007', '3T6903', '3.03'], ['48', '4', '"Sin City"', 'Charles Beeson', 'Robert Singer & Jeremy Carver', 'October25,2007', '3T6904', '3.02'], ['49', '5', '"Bedtime Stories"', 'Mike Rohl', 'Cathryn Humphris', 'November1,2007', '3T6905', '3.24'], ['50', '6', '"Red Sky at Morning"', 'Cliff Bole', 'Laurence Andries', 'November8,2007', '3T6906', '3.01'], ['51', '7', '" Fresh Blood "', 'Kim Manners', 'Sera Gamble', 'November15,2007', '3T6907', '2.88'], ['52', '8', '" A Very Supernatural Christmas "', 'J. Miller Tobin', 'Jeremy Carver', 'December13,2007', '3T6908', '3.02'], ['53', '9', '"Malleus Maleficarum"', 'Robert Singer', 'Ben Edlund', 'January31,2008', '3T6909', '2.95'], ['56', '12', '"Jus in Bello"', 'Phil Sgriccia', 'Sera Gamble', 'February21,2008', '3T6911', '3.23'], ['57', '13', '"Ghostfacers"', 'Phil Sgriccia', 'Ben Edlund', 'April24,2008', '3T6913', '2.22'], ['58', '14', '"Long Distance Call"', 'Robert Singer', 'Jeremy Carver', 'May1,2008', '3T6914', '2.63'], ['59', '15', '"Time Is on My Side"', 'Charles Beeson', 'Sera Gamble', 'May8,2008', '3T6915', '2.55']]}