The ornamental design for an interlockingstep, as shown and described.
FIG. 1 is a perspective view of the interlocking step;
FIG. 2 is a right side view of the interlocking step, the mirror image being the left side view;
FIG. 3 is a top view of the interlocking step;
FIG. 4 is a front view of the interlocking step;
FIG. 5 is a rear view of the interlocking step;
FIG. 6 is a bottom perspective view of the interlocking step; and,
FIG. 7 is an environmental front perspective view of three (3) interlocking steps depicted in a stacked and interlocked orientation.
In the figures, the broken lines are for illustrative purposes only and, in FIG. 7, are also for showing of additional interlocking steps for the purpose of illustrating environment; the broken lines form no part of the claimed design. The break lines are for illustrating the indefinite width of the interlocking step only and form no part of the claimed design.