get_stadiamap() accesses a tile server for Stadia Maps and
downloads/stitches map tiles/formats a map image.
Arguments
- bbox
 a bounding box in the format c(lowerleftlon, lowerleftlat, upperrightlon, upperrightlat).
- zoom
 a zoom level
- maptype
 stamen_terrain, stamen_toner, stamen_toner_lite, stamen_watercolor, stamen_terrain_background, stamen_toner_background, stamen_terrain_lines, stamen_terrain_labels, stamen_toner_lines, stamen_toner_labels.
- crop
 crop raw map tiles to specified bounding box. if FALSE, the resulting map will more than cover the bounding box specified.
- messaging
 turn messaging on/off
- urlonly
 return url only
- color
 color or black-and-white (use force = TRUE if you've already downloaded the images)
- force
 if the map is on file, should a new map be looked up?
- where
 where should the file drawer be located (without terminating "/")
- ...
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