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 input string. If no emails are found, the function 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 emails here")==[]
  assert find_emails("Invalid email format: john@, jane@example")==[]
  assert find_emails("Multiple domains: john@example.com, jane@test.org, and eve@example.co.uk")==["john@example.com", "jane@test.org", "eve@example.co.uk"]
  assert find_emails("")==[]
output: import re
  
  def find_emails(text):
      pattern = r'[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}'
      return re.findall(pattern, text)