Which of the following code snippets can be used to complete the code, to check if a given triangle is equilateral$($all sides are equal$),$ isosceles$($any two sides are equal$),$ or scalene$($no sides are equal$)$:

x $=6$

y $=8$

z $=12$

if x $==$ y $==$ z:

# missing code $1$

elif x$==$y or y$==$z or z$==$x:

# missing code $2$

else:

# missing code $3$