Write a function to print check if the triangle is isosceles or not.
def check_isosceles(x,y,z):
  if x==y or y==z or z==x:
	   return True
  else:
     return False
<s>[INST]<<SYS>>Given a task and its code, generate test cases for the code.<</SYS>>Write a function to print check if the triangle is isosceles or not.
def check_isosceles(x,y,z):
  if x==y or y==z or z==x:
	   return True
  else:
     return False[/INST]assert check_isosceles(6,8,12)==False 
assert check_isosceles(6,6,12)==True
assert check_isosceles(6,16,20)==False</s>