In assessing fair use, one of the factors that must be included in the analysis is ???the amount and substantiality of the portion used in relation to the copyrighted work as a whole.??? 17 U.S.C. ??? 107(3) (emphasis added); see also 17 U.S.C. ?????? 107(2) (referring to the ???nature of the copyrighted work???), 107(4) (referring to the ???value of the copyrighted work???).