input: Write a function to extract all email addresses from a given string. The function should return a list of 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("This string has no emails.")==[]
  assert find_emails("")==[]
output: import re
  
  def find_emails(text):
      pattern = r'\b[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Z|a-z]{2,}\b'
      return re.findall(pattern, text)