input: Write a function to extract all email addresses from a given string. If the string contains no email addresses, return an empty list. The function should use regular expressions to identify and extract the email addresses.
  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 email addresses in this string.")==[]
  assert find_emails("Here is an email: test@example.com")==["test@example.com"]
  assert find_emails("")==[]
  assert find_emails("Multiple emails: user1@example.com, user2@example.com")==["user1@example.com", "user2@example.com"]
output: import re
  
  def find_emails(text):
      return re.findall(r'[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}', text)