input: Write a function to generate a random password that consists of 8 characters using a combination of letters and digits. If the function is called, it should return a string of 8 random characters.
  assert generate_password()==("aB3dF6h8")
  assert generate_password()==("9Zx2E5q0")
  assert generate_password()==("1mN7pL4R")
  assert generate_password()==("W5wKj8Xc")
  assert generate_password()==("2bV6yT9z")
output: import random
  import string
  
  def generate_password():
      return ''.join(random.choices(string.ascii_letters + string.digits, k=8))