def __init__(self, database, head, subs):
        """
        The head and subs are essential - what makes this struct.
        The database should only be used while structs are constructed,
        and later removed.
        """
        self.database = database
        self.head = head
        self.subs = subs
        self.prev = None
        self.next = None        
        self.forwardchain_body = None
        self.conditional_body = None
        self.forwardchain_head = None
        self.conditional_head = None

        The head and subs are essential - what makes this struct.
        The database should only be used while structs are constructed,
        and later removed.
        
recipes/Python/413570_ExtensiPythologic__Prolog_syntax/recipe-413570.py