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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _meters_per_pixel(zoom, lat=0.0, tilesize=256):
 """ Return the pixel resolution for a given mercator tile zoom and lattitude. Parameters zoom: int Mercator zoom level lat: float, optional Latitude in decimal degree (default: 0) tilesize: int, optional Mercator tile size (default: 256). Returns ------- Pixel resolution in meters """

    return (math.cos(lat * math.pi / 180.0) * 2 * math.pi * 6378137) / (
        tilesize * 2 ** zoom
    )