docs: def epsg_code(geojson):
      """ get the espg code from the crs system """
  
      if isinstance(geojson, dict):
          if 'crs' in geojson:
              urn = geojson['crs']['properties']['name'].split(':')
              if 'EPSG' in urn:
                  try:
                      return int(urn[-1])
                  except (TypeError, ValueError):
                      return None
  
      return None