You need to capture from regex. search for the pattern, if found, retrieve the string using group(index). Assuming valid checks are performed:
>>> p = re.compile("name (.*) is valid")>>> result = p.search(s)>>> result<_sre.SRE_Match object at 0x10555e738>>>> result.group(1) # group(1) will return the 1st capture (stuff within the brackets). # group(0) will returned the entire matched text.'my_user_name'