The ornamental design for a sewingmachine, as shown and described.
FIG. 1 is a perspective view of a sewing machine;
FIG. 2 is a front view thereof;
FIG. 3 is a top view thereof;
FIG. 4 is a right-side view thereof;
FIG. 5 is a left-side view thereof;
FIG. 6 is a rear view thereof; and,
FIG. 7 is a bottom view thereof.
The broken lines depict environmental subject matter only and form no part of the claimed design. The dot chain lines illustrate a boundary between claimed and unclaimed portions and form no part of the claimed design.