This is not the most efficient algorithm, but to implement it:
prime = {x for x in range(2, 100) if all(x % y != 0 for y in range(2, x))}
Or, equivalently:
prime = {x for x in range(2, 100) if not any(x % y == 0 for y in range(2, x))}
For one simple refinement, you can stop checking for possible factors once you've passed the square root of x
:
prime = {x for x in range(2, 100) if all(x % y != 0 for y in range(2, int(math.floor(math.sqrt(x))) + 1))}