We claim; the ornamental design for a leaf pre-skimmer for a pool, as shown and described.
FIG. 1 is a top, side perspective view of my design, the opposite side view being identical, showing depth, thereto;
FIG. 2 is a front view, the back view being identical thereto;
FIG. 3 is a side view, the opposite side being identical thereof; and,
FIG. 4 is a top view thereof; the bottom being open.
The ----(dash, dash, dash) lines in FIG. 1 represent the interface between the concrete walking surface and the pool side and forms no part of the claimed design.