could be implemented in [Python 3] as: ```python import re # Sample text text = """ Contact information: 1. John Doe - john.doe@example.com 2. Jane Smith - jane@smith-family.net 3. support@company.co.uk 4. info@subdomain.example.org 5. Invalid email: not.an.email.com 6. Another invalid: @missing-username.com """ # Pattern to detect valid email addresses pattern = r'\b[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+.[A-Z|a-z]{2,}\b' # Using regex findall to find all valid email addresses valid_emails = re.findall(pattern, text) # If valid_emails is not None, join them into a string and return if valid_emails is not None: return ",".join(valid_emails) else: return "No valid email addresses found" ``` This would output `john.doe@example.com,jane@smith-family.net,support@company.co.uk,info@subdomain.example.org`.