Fan

FIG. 1 is a top front isometric view of a fan showing the claimed design; FIG. 2 is a front elevation view thereof; FIG. 3 is a rear elevation view thereof; FIG. 4 is a left side elevation view thereof; FIG. 5 is a right side elevation view thereof; FIG. 6 is a top plan view thereof; FIG. 7 is a bottom plan view thereof; and, FIG. 8 is a bottom rear isometric view thereof. The broken lines in the figures show portions of the fan that form no part of the claimed design.