Using a regular expression pattern to identify valid email addresses, we can extract them as follows: ```python import re text_input = """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""" # Regular expression for matching email addresses email_pattern = r'[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}' valid_emails = re.findall(email_pattern, text_input) # Join the addresses into a comma-separated string result = ','.join(valid_emails) # Replacing any spaces that are erroneously included in the return value result = result.replace(' ', '') print(result) ``` The answer extracted using this code snippet would be: "john.doe@example.com,jane@smith-family.net,support@company.co.uk,info@subdomain.example.org"