input: Write a function to validate a list of emails. The function should return a boolean indicating whether a given email address is valid. If the given list is empty then return True.
  def validate_mail_list(mail_list):
      for mail in mail_list:
          if not re.match("[^@]+@[^@]+\.[^@]+", mail):
              return False
      return True
  assert validate_mail_list(["example.user@gmail.com", "bad@example"])==False
  assert validate_mail_list(["example.user@gmail.com", "good@example.com"])==True
  assert validate_mail_list(["invalid@.com", "wrong@example@.com"])==False
  assert validate_mail_list([])==True
output: def validate_mail_list(mail_list):
      if not mail_list:
          return True
      for mail in mail_list:
          if not re.match("[^@]+@[^@]+\.[^@]+", mail):
              return False
      return True