input: Write a function to extract all email addresses from a given string using regular expressions. If the string contains no email addresses, return an empty list. If the string contains multiple email addresses, return a list of all found email addresses.
  
  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("") == []
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
  