input: Write a function to extract all email addresses from a given string. Implement a regular expression to match valid email addresses and return them as a list. If the input string is empty, 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 just text") == []
  assert find_emails("Email: test@email.com") == ["test@email.com"]
  assert find_emails("") == []
output: import re
  
  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