input: Write a function to extract all email addresses from a given string using a regular expression. The function should return a list of all email addresses found in the string. If no email addresses are found, it should return an empty list.
  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 here")==[]
  assert find_emails("")==[]
output: import re
  
  def find_emails(text):
      return re.findall(r'[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}', text)