code: def gps_distance(latlon_1, latlon_2):
      '''
      Distance between two (lat,lon) pairs.
  
      >>> p1 = (42.1, -11.1)
      >>> p2 = (42.2, -11.3)
      >>> 19000 < gps_distance(p1, p2) < 20000
      True
      '''
      x1, y1, z1 = ecef_from_lla(latlon_1[0], latlon_1[1], 0.)
      x2, y2, z2 = ecef_from_lla(latlon_2[0], latlon_2[1], 0.)
  
      dis = math.sqrt((x1 - x2) ** 2 + (y1 - y2) ** 2 + (z1 - z2) ** 2)
  
      return dif gps_distance(latlon_1, latlon_2):
      '''
      Distance between two (lat,lon) pairs.
  
      >>> p1 = (42.1, -11.1)
      >>> p2 = (42.2, -11.3)
      >>> 19000 < gps_distance(p1, p2) < 20000
      True
      '''
      x1, y1, z1 = ecef_from_lla(latlon_1[0], latlon_1[1], 0.)
      x2, y2, z2 = ecef_from_lla(latlon_2[0], latlon_2[1], 0.)
  
      dis = math.sqrt((x1 - x2) ** 2 + (y1 - y2) ** 2 + (z1 - z2) ** 2)
  
      return dis
docs: Distance between two (lat,lon) pairs.
  
      >>> p1 = (42.1, -11.1)
      >>> p2 = (42.2, -11.3)
      >>> 19000 < gps_distance(p1, p2) < 20000
      True