正如您的问题的注解所指出的，您的代码中有几个错误。
下面是运行良好的代码版本。

prime = [2]
i = 3
while len(prime) <= 1000:
    testlist = []
    for number in prime:
        testlist.append(i % number)
    if 0 not in testlist:
        prime.append(i)
    i = i + 1
print prime

我还没有测试，但你可以创建如下方法：

def get_prime_no_upto(number):
  start = 2
  primes = list(range(start,number)).to_a
  for no in range(start,number):
    for num in range(start,no):
      if ( no % num  == 0) and (num != no):
        primes.delete(no)
        break
  primes

并且可以像使用

print primeno(100)

干杯！

def prime_checker(number):
    stop = False
    prime = True
    n = 2
    while stop == False and n < number:
        if (number) % n == 0:
            prime = False
            stop = True
        n += 1
    if prime == True:
        print("It's a prime number.")
    elif prime == False:
        print("It's not a prime number.")

prime_checker(11)