Question: A "Seussical" lyricist collaborated with Stephen Flaherty on a musical based on a screen play written by which person?

Context paragraphs:
Chita Rivera: The Dancer's Life: Chita Rivera: The Dancer's Life is a musical revue based on the life of Chita Rivera, with a book by Terrence McNally and new songs by Stephen Flaherty and Lynn Ahrens as well as songs from various other composers.  It earned Rivera her ninth Tony Award nomination (for Best Actress in a Musical).

Dessa Rose (musical): Dessa Rose is a musical based on the book by Sherley Anne Williams with book and lyrics by Lynn Ahrens and music by Stephen Flaherty.  It tells the story of a young black woman and a young white woman and their journey to acceptance in 1847 in the ante-bellum South, as they tell their story to their grandchildren.

Journey to the Past: "Journey to the Past" is a song from the 1997 20th Century Fox animated feature film, "Anastasia".  It was written by lyricist Lynn Ahrens and composer Stephen Flaherty, and originally recorded by American actress and singer Liz Callaway in her role as the singing voice of the film's title character, Anastasia.  A pop rendition recorded by American R&B recording artist Aaliyah is played over the film's end credits, and was released as a single from the film's soundtrack album.  "Journey to the Past" is a predominantly pop ballad that is influenced by contemporary R&B music.

Stephen Flaherty: Stephen Flaherty (born September 18, 1960) is an American composer of musical theatre.  He works most often in collaboration with the lyricist/bookwriter Lynn Ahrens.  They are best known for writing the Broadway musicals "Once on This Island", which was nominated for eight Tony Awards, "Seussical", which was nominated for the Grammy Award, and "Ragtime", which was nominated for twelve Tony Awards and won Best Original Score.  Flaherty was also nominated for two Academy Awards and two Golden Globe Awards with Lynn Ahrens for his songs and song score for the animated film musical "Anastasia".

Rocky the Musical: Rocky the Musical (originally Rocky: Das Musical) is a 2012 musical with music and lyrics by Stephen Flaherty and Lynn Ahrens, with a book by Thomas Meehan, adapted from a screenplay by Sylvester Stallone.  The show held its world premiere in Hamburg in 2012 and opened on Broadway in 2014 at the Winter Garden Theatre.  The show roughly follows the plot of the 1976 film "Rocky".

Lynn Ahrens: Lynn Ahrens (born October 1, 1948) is an American writer and lyricist for the musical theatre, television and film.  She has collaborated with Stephen Flaherty for many years.  She won the Tony Award, Drama Desk Award, and Outer Critics Circle Award for the Broadway musical "Ragtime".  Together with Flaherty, they have written many musicals, including "Lucky Stiff", "Once on This Island", "My Favorite Year", "Ragtime", "Seussical", "A Man of No Importance", "Dessa Rose", "The Glorious Ones", and most recently seen on Broadway, "Rocky the Musical".

Anastasia (musical): Anastasia is a musical with music and lyrics by Lynn Ahrens and Stephen Flaherty, and a book by Terrence McNally.  Based on the 1997 film of the same name, the musical tells the story of the legend of Grand Duchess Anastasia Nikolaevna of Russia, which claims that she, in fact, escaped the execution of her family.  Anastasia, who appears in the plot as an amnesiac orphan named Anya, hopes to find some trace of her family, but sides with con men who wish to take advantage of her likeness to the Grand Duchess.

Seussical: Seussical is a musical by Lynn Ahrens and Stephen Flaherty based on the stories of Dr. Seuss (mainly "Horton Hears a Who! ", "Horton Hatches the Egg" and "Miss Gertrude McFuzz") that debuted on Broadway in 2000.  The play's story is a complex amalgamation of many of Seuss's most famous books.  After a Broadway run, the production spawned two US national tours and a UK tour.  It has become a beloved classic for schools, communities, and regional theatres.

Screen Play (blog): Screen Play is an online forum focusing on Australian videogame culture.  Between May 2006 and April 2014 Screen Play was a blog in Fairfax Media newspapers The Age (Melbourne), The Sydney Morning Herald, The Brisbane Times and WA Today.  Screen Play was founded by Jason Hill and featured regular contributions by journalist James "DexX" Dominguez.  Both the Brisbane Times and WA Today began mirroring the blog on 26 June 2009.

Lucky Stiff: Lucky Stiff is a musical farce.  It was the first collaboration for the team of Lynn Ahrens (book and lyrics) and Stephen Flaherty (music).  The show is based on the 1983 novel "The Man Who Broke the Bank at Monte Carlo" by Michael Butterworth.  It was created and performed at Playwrights Horizons off-Broadway in 1988, and won the Richard Rodgers Award for that year.  The musical was seen in London's West End in 1997 but has not had a Broadway production.  A film version had a limited release in theatres in 2015 but received mostly negative reviews.

Supporting paragraphs: Lynn Ahrens Rocky the Musical
Answer: Sylvester Stallone