input: def list_primes_until(m):
      """Write a function that receives a non-negative integer and returns a list of all prime numbers less than m.
      for example:
      list_primes_until(5) => [2,3]
      list_primes_until(11) => [2,3,5,7]
      list_primes_until(0) => []
      list_primes_until(20) => [2,3,5,7,11,13,17,19]
      list_primes_until(1) => []
      list_primes_until(18) => [2,3,5,7,11,13,17]
      """
output:     if m <= 2:
          return []
      
      primes = []
      
      for num in range(2, m):
          is_prime = True
          for i in range(2, int(num ** 0.5) + 1):
              if num % i == 0:
                  is_prime = False
                  break
          if is_prime:
              primes.append(num)
      
      return primes