input: 
  from typing import List
  
  def extract_emails(text: str) -> List[str]:
      """ This function takes a string and extracts all email addresses from it.
      >>> extract_emails("This is an example with two emails: john@example.com, and jane@example.com")
      ['john@example.com', 'jane@example.com']
      """
  
output:     import re
      pattern = r'\b[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Z|a-z]{2,}\b'
      return re.findall(pattern, text)