pub fn is_register_to_token(
    token: &ContractAccount<TestToken>, 
    account_id: ValidAccountId
) -> bool {
    let sb = view!(token.storage_balance_of(account_id)).unwrap_json_value();
    if let Value::Null = sb {
        false
    } else {
        true
    }
}
/// tell a user if he has registered to given ft token
tell a user if he has registered to given ft token
tell a user if he has registered to given ft token
pub fn is_register_to_token(
    token: &ContractAccount<TestToken>, 
    account_id: ValidAccountId
) -> bool {
    let sb = view!(token.storage_balance_of(account_id)).unwrap_json_value();
    if let Value::Null = sb {
        false
    } else {
        true
    }
}
pub fn is_register_to_token ( token : & ContractAccount < TestToken > , account_id : ValidAccountId ) -> bool { let sb = view ! ( token storage_balance_of ( account_id ) ) . unwrap_json_value ( ) ; if let Value :: Null = sb { false } else { true } }
tell a user if he has registered to given ft token
tell a user if he has registered to given ft token
token
&ContractAccount<TestToken>
account_id
ValidAccountId
token
&ContractAccount<TestToken>
account_id
ValidAccountId