input: Write a function to extract all email addresses from a given string using regular expressions. The function should return a list of all found email addresses. If no email addresses are found, it should return an empty list. If the input string is empty, it should also 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 emails here.")==[]
  assert find_emails("")==[]
output: import re
  
  def find_emails(text):
      if not text:
          return []
      emails = re.findall(r'[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}', text)
      return emails