  (0) the purpose and character of the use, including whether such use is of a commercial nature or is for nonprofit educational purposes; (0) the nature of the copyrighted work; (0) the amount and substantiality of the portion used in relation to the copyrighted work as a whole; and (0) the effect of the use upon the potential market for or value of the copyrighted work. The fact that a work is unpublished shall not itself bar a finding of fair use if such finding is made upon consideration of all the above factors.