Shoelace Mystery

I trotted over to the front entryway to see what was by the door, and I bumped right into a pair of big green sneakers! One of the shoes had a long, braided white lace trailing onto the floor mat. Thinking it was a wiggly friend, I pounced on the plastic tip with both paws, but it didn't wiggle back at all. I tugged gently with my nose, pulling the loop loose until the knot came untied with a soft slither. Now both sides are lying flat across the mat, totally unknotted and quiet.