Nervous System included a second single which was co-written by which frequent writing partner?
Nervous System (EP): Uh Huh", the second single from "Nervous System", was released on June 2, 2017. Uh Huh (Julia Michaels song): "Uh Huh" is a song by American singer and songwriter Julia Michaels. Uh Huh (Julia Michaels song):  The song was written by Michaels and her frequent writing partner Justin Tranter, along with the song's producers, Mattias Larsson and Robin Fredriksson.
Justin Tranter