input: Write a function to extract all email addresses from a given string using regular expressions. If the given string is empty then return an empty list. The function should return a list of all valid email addresses found in the input string.
  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("Multiple emails: joe@example.com, bob@example.net, alice@domain.org")==['joe@example.com', 'bob@example.net', 'alice@domain.org']
  assert find_emails("Check this invalid email: invalid.email.@example.com")==[]
  assert find_emails("")==[]
output: import re
  
  def find_emails(text):
      if not text:
          return []
      pattern = r'\b[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Z|a-z]{2,}\b'
      return re.findall(pattern, text)