The ornamental design for a breathingtrainer, as shown and described.
FIG. 1 is a perspective view of a breathing trainer, showing my new design;
FIG. 2 is another perspective view thereof;
FIG. 3 is a front elevational view thereof, the rear elevational view being a mirror image of FIG. 3;
FIG. 4 is a left side view thereof;
FIG. 5 is a right side view thereof;
FIG. 6 is a top plan view thereof, the bottom plan view is identical; and,
FIG. 7 is a partial enlarged view of FIG. 1.
The broken lines in the figures are for the purposes of illustrating portions of the breathing trainer which form no part of the claimed design. The broken line circles in FIGS. 1 and 7 depict the bounds of the enlargement and form no part of the claimed design.