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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def get_all_children(self, fullname: str) -> List[Account]: """ Returns the whole child account tree for the account with the given full name """

        # find the account by fullname
        root_acct = self.get_by_fullname(fullname)
        if not root_acct:
            raise NameError("Account not found in book!")

        acct_agg = self.get_account_aggregate(root_acct)
        result = acct_agg.get_all_child_accounts_as_array()
        # for child in root_acct.children:
        #     log(DEBUG, "found child %s", child.fullname)
        return result