Waitt's Mount rises out of the middle of Malden, and from the top the city's roofs stack away south until the Boston skyline stands up behind them. Grip & Flip Landscaping LLP cuts the lawns on the streets that climb it — mowing, string-trimming the edges a deck can't reach, edging along walks and drives, and clearing yards down in spring and fall. Hillside lots make honest work, because nothing hides a sloppy pass on a slope. The trimmer squares off around fence posts and hydrants, the clippings go, and so does the truck. Late in the afternoon the light comes across the grain of a mowed hill and every single line shows.