def all_primes(start,end):
    list_nonprimes = []
    list_primes = []

    for i in range(start,end):
        if i in list_nonprimes: continue
        if i in list_primes: continue

        if i == 2 :
            list_primes.append(i)

        if i%2 == 0: 
            list_nonprimes.append(i)
        
        for a in range(3,int(i**0.5)+1,2):
            if i % a == 0 :
                list_nonprimes.append(i)
                break

        if i not in list_nonprimes: list_primes.append(i)            

    return list_primes

start = 2
end = 10
print all_primes(start, end)

[2, 3, 5, 7]