I need help

import random

COLORS = ['yellow', 'red', 'blue', 'green']

class Monster(object): min_hit_points = 1 max_hit_points = 1 min_experience = 1 max_experience = 1 weapon = 'sword' sound = 'roar'

def __init__(self, **kwargs):
    self.hit_points =random.randint(self.min_hit_points, self.max_hit_points)
    self.experience =random.randint(self.min_experience, self.max_experience)
    self.color = random.choice(COLORS)

    for key, value in kwargs.items():
        setattr(self, key, value)   

def battlecry(self):
    return self.sound.upper() 

class Goblin(Monster): max_hit_points = 3 max_experience = 2 sound = 'hob'

class Troll(Monster): max_hit_points = 5 min_hit_points = 3 min_experience = 2 max_experience = 6 sound = 'hows'

class Dragon(Monster): max_hit_points = 8 min_hit_points = 9 min_experience = 5 max_experience = 2 sound = 'grall'

I wrote this quote and after I saved it and I typed the code:

import monster jake = monster.Dragon()

and I got this error

Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/home/treehouse/workspace/monster.py", line 15, in init
self.hit_points =random.randint(self.min_hit_points, self.max_hit_points)
File "/usr/local/pyenv/versions/3.5.0/lib/python3.5/random.py", line 218, in randint
return self.randrange(a, b+1)
File "/usr/local/pyenv/versions/3.5.0/lib/python3.5/random.py", line 196, in randrange
raise ValueError("empty range for randrange() (%d,%d, %d)" % (istart, istop, width))
ValueError: empty range for randrange() (9,9, 0)

I don't understand what it is

help me