Toy Building Block

FIG. 1 is a perspective view of a toy building block showing my new design; FIG. 2 is a front view thereof; FIG. 3 is a rear view thereof; FIG. 4 is a left side view thereof; FIG. 5 is a right side view thereof; FIG. 6 is a top view thereof; and, FIG. 7 is a bottom view thereof. The broken lines shown in the figures and the lower opacity areas within the broken lines are for the purpose of illustrating portions of the toy building block that form no part of the claimed design.