FIG. 1 is a left side elevational view of the gate kepper for a snap hook; FIG. 2 is a right side elevational view thereof; FIG. 3 is a top plan view thereof; FIG. 4 is a front elevational view thereof; FIG. 5 is a rear elevational view thereof; FIG. 6 is an environmental top plan view thereof; and, FIG. 7 is an environmental side view thereof. The broken lines shown in FIGS. 6 and 7 are for illustrative purposes only and form no part of the claimed design.