class Spider:
    """ I am a quadruped spider with four legs consisting of coxa, femur and tibia each"""
    def __init__(self):
        self.fl = Leg(0, 0,  1,  2)
        self.fr = Leg(1, 3,  4,  5)
        self.rl = Leg(2, 6,  7,  8)
        self.rr = Leg(3, 9, 10, 11)

...
class Leg:
    """ I am a single leg of the spider consisting of coxa, femur and tibia"""
    def __init__(self, legId,coxaId, femurId, tibiaId):
        self.legId=legId
        self.coxa = Extremity('coxa', coxaId)
        self.femur = Extremity('femur', femurId,legId<2)
        self.tibia = Extremity('tibia', tibiaId,legId<2)

...
class Servo:
    """ I am a single Servo motor """
    def __init__(self, id,inverted=False):
        self.id = id
        self.inverted=inverted

    def setAngle(self, angle):
        self.angle = angle
        trueAngle=180-angle if self.inverted else angle
        if kit is not None:
            kit.servo[self.id].angle = trueAngle
        return trueAngle

# Test Adafruit 
# WF 2019-07-09
import sys
import time
from adafruit_servokit import ServoKit
kit = ServoKit(channels=16)

# 
# set the given angle for the given servos
#
def setAngle(servos,angle):
  print (angle)
  for id in servos:
    kit.servo[id].angle=angle
  time.sleep(0.3)

# Test Servo Software
servos=[]
args=len(sys.argv)
fromangle=0
toangle=180
step=1
if args>1:
  for port in range(1,args-1,1):
    servos.append(int(sys.argv[port]))
  anglestr=sys.argv[args-1]
  if "-" in anglestr:
    parts=anglestr.split("-") 
    fromangle=int(parts[0])
    toangle=int(parts[1])
  else:
    fromangle=int(anglestr)
    toangle=fromangle
else:
  servos.append(0)
  servos.append(1)
  servos.append(2)

if fromangle!=toangle:
  try:
    while True:
      for setangle in range(fromangle,toangle+step,step):
        setAngle(servos,setangle)
  except KeyboardInterrupt:
    print("Keyboard interrupt")
else:
  setAngle(servos,fromangle)