input: Write a python function to extract email addresses from a given string using regular expressions.
  assert extract_emails("The list of contacts is john@test.com,jane@example.com,bob@test.com") == ['john@test.com', 'jane@example.com', 'bob@test.com']
  assert extract_emails("Please contact us at support@company.com or sales@company.com.") == ['support@company.com', 'sales@company.com']
  assert extract_emails("No emails here!") == []
output: def extract_emails(text):
      import re
      return re.findall(r'\b[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Z|a-z]{2,}\b', text)