input: Write a function to determine if a given number is a prime number. The function should take an integer as input and return True if the number is prime, otherwise it should return False.
  assert is_prime(17)==True
  assert is_prime(15)==False
  assert is_prime(2)==True
  assert is_prime(1)==False
  assert is_prime(29)==True
output: def is_prime(n):
      if n <= 1:
          return False
      if n == 2:
          return True
      if n % 2 == 0:
          return False
      for i in range(3, int(n**0.5) + 1, 2):
          if n % i == 0:
              return False
      return True