about django's list_fields in making models for friends list, in project about making SNS

i'm amateur django student. i'm making web-SNS like instagram. So, i should make models that contains one user's all friends. so i try to use list for containing user's friends. like this photo

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yeah, i know i can't use and build list by using that way. how to make use list for save user's friends list? or Is there more good idea for saving user's friends list in user(not User, just real user)'s model?