class MyPrimes:
    def __init__(self, start, end):
        self.start = start
        self.end = end
    def isPrimes(self, item):
        if item <= 1:
            return False
        for y in range(2, item):
            if item % y == 0:
                return False
        return True
    def __iter__(self):
        self.cur_val = self.start
        return self
    def __next__(self):
        for item in range(self.cur_val, self.end):
            if self.isPrimes(item):
                self.cur_val = item + 1
                return item
        raise StopIteration

print([x for x in MyPrimes(5, 20)])