class_docstr: Use spherical geometry to calculate the surface distance between
  points.
  
  Set which radius of the earth to use by specifying a ``radius`` keyword
  argument. It must be in kilometers. The default is to use the module
  constant `EARTH_RADIUS`, which uses the average great-circle radius.
  
  Example::
  
      >>> from geopy.distance import great_circle
      >>> newport_ri = (41.49008, -71.312796)
      >>> cleveland_oh = (41.499498, -81.695391)
      >>> print(great_circle(newport_ri, cleveland_oh).miles)
      536.997990696
code: def measure(self, a, b):
      a, b = Point(a), Point(b)
      _ensure_same_altitude(a, b)
  
      lat1, lng1 = radians(degrees=a.latitude), radians(
          degrees=a.longitude
      )
      lat2, lng2 = radians(degrees=b.latitude), radians(
          degrees=b.longitude
      )
  
      sin_lat1, cos_lat1 = sin(lat1), cos(lat1)
      sin_lat2, cos_lat2 = sin(lat2), cos(lat2)
  
      delta_lng = lng2 - lng1
      cos_delta_lng, sin_delta_lng = cos(delta_lng), sin(delta_lng)
  
      d = atan2(
          sqrt(
              (cos_lat2 * sin_delta_lng) ** 2
              + (
                  cos_lat1 * sin_lat2
                  - sin_lat1 * cos_lat2 * cos_delta_lng
              )
              ** 2
          ),
          sin_lat1 * sin_lat2 + cos_lat1 * cos_lat2 * cos_delta_lng,
      )
  
      return self.RADIUS * d
  
imports: from math import asin, atan2, cos, sin, sqrt
  from geographiclib.geodesic import Geodesic
  from geopy import units, util
  from geopy.point import Point
  from geopy.units import radians
label_desc: Use image node_id 2 for calling the great_circle obj's underlying member method code with example usage: obj.measure(a, b) and returns: unknown