What is the test for a disability discrimination claim under the Rehabilitation Act?

To state a prima facie case of disability discrimination under the Rehabilitation Act, a plaintiff must demonstrate that she is a "qualified individual." See 29 U.S.C. 794(a). "The term 'qualified individual' means an individual who, with or without reasonable accommodation, can perform the essential functions of the employment position that such individual holds or desires." 42 U.S.C. 12111(8). The term "essential functions," in turn, refers to the "fundamental job duties of th[at] employment position." 29 C.F.R. 1630.2(n)(1); see id. 1630.2(n)(2)(i)-(iii) (describing why a "job function may be considered essential"); see also Dark v. Curry County, 451 F.3d 1078, 1087 (9th Cir. 2006).