import re
regex = r"\bself\._\w*|(\w+\.\_\w+)"
test_str = ("object._attr self._attr object._attr\n"
"a._aaa\n"
"self._attr\n"
"object._")
print(list(filter(None, re.findall(regex, test_str))))
aW1wb3J0IHJlCgpyZWdleCA9IHIiXGJzZWxmXC5fXHcqfChcdytcLlxfXHcrKSIKCnRlc3Rfc3RyID0gKCJvYmplY3QuX2F0dHIgc2VsZi5fYXR0ciBvYmplY3QuX2F0dHJcbiIKCSJhLl9hYWFcbiIKCSJzZWxmLl9hdHRyXG4iCgkib2JqZWN0Ll8iKQoKcHJpbnQobGlzdChmaWx0ZXIoTm9uZSwgcmUuZmluZGFsbChyZWdleCwgdGVzdF9zdHIpKSkp