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 left view thereof;
FIG. 4 is a rear view thereof;
FIG. 5 is a right view thereof;
FIG. 6 is a top view thereof; and,
FIG. 7 is a bottom view thereof.
The broken line showing fasteners, flywheel, and additional parts is included for the purpose of illustrating environmental structure and forms no part of the claimed design.