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):
      if not mail_list:
          return True
      for mail in mail_list:
          if not re.match("[^@]+@[^@]+\.[^@]+", mail):
              return False
      return True
  
  assert validate_mail_list(["example.user@gmail.com", "another.user@yahoo.com"]) == True
  assert validate_mail_list(["example@domain", "user@.com", "user.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