input: Write a function to extract all email addresses from a given string and return them as a list. If there are no email addresses, return an empty list.
  def find_emails(text):
      regex = r"([a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\.[a-zA-Z0-9-.]+)"
      emails = re.findall(regex, text)
      return emails
  assert find_emails("This is an example with two emails: john@example.com, and jane@example.com")==["john@example.com", "jane@example.com"]
  assert find_emails("No emails here.")==[]
  assert find_emails("email1@domain.com is valid, but email@domain is not.")==["email1@domain.com"]
  assert find_emails("")==[]
  assert find_emails("test@example.com test2@example.com")==["test@example.com", "test2@example.com"]
output: 
  def find_emails(text):
      regex = r"([a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\.[a-zA-Z0-9-.]+)"
      emails = re.findall(regex, text)
      return emails
  