Vacuum

FIG. 1 is a perspective view for an embodiment of a vacuum; FIG. 2 is a front elevation view of a vacuum; FIG. 3 is a back elevation view of a vacuum; FIG. 4 is a left elevation view of a vacuum; FIG. 5 is a right elevation view of a vacuum; FIG. 6 is a top elevation view of a vacuum; and, FIG. 7 is a bottom elevation view of a vacuum. The dashed lines in the drawings illustrate portions of the handle, battery handle, lithium-ion battery handle and/or portions thereof that form no part of the claimed design. The surface shading and contour lines (including any CAD or wire frame lines) in the drawings is a drawing convention to represent character and contour; it does not illustrate material, surface ornamentations, or surface decoration and forms no part of the claimed design.