input: Write a function to extract all email addresses from a given string using a regular expression pattern. The function should return a list of all found email addresses.
  
  def find_emails(text):
      regex = r"([a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\.[a-zA-Z0-9-.]+)"
      emails = re.findall(regex, text)
      return emails
  
  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("Here are some emails: alice@domain.com, bob@subdomain.domain.com")==["alice@domain.com", "bob@subdomain.domain.com"]
  assert find_emails("No valid emails in this string")==[]
  assert find_emails("")==[]
output: import re
  
  def find_emails(text):
      regex = r"([a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\.[a-zA-Z0-9-.]+)"
      emails = re.findall(regex, text)
      return emails