pub fn buy(&mut self, expected: Option<ExpectedRate>, to: Option<AccountId>);

pub fn sell(&mut self, amount: U128, expected: Option<ExpectedRate>) -> Promise;

pub fn contract_status(&self) -> ContractStatus;
pub fn name(&self) -> String;
pub fn symbol(&self) -> String;
pub fn decimals(&self) -> u8;
pub fn spread(&self, amount: Option<U128>) -> U128;
pub fn version(&self) -> String;
pub fn blacklist_status(&self, account_id: &AccountId) -> BlackListStatus;
pub fn owner(&self);

pub fn ft_transfer(&mut self, receiver_id: AccountId, amount: U128, memo: Option<String>);
pub fn ft_transfer_call(
        &mut self,
        receiver_id: AccountId,
        amount: U128,
        memo: Option<String>,
        msg: String,
    ) -> PromiseOrValue<U128>;
pub fn ft_total_supply(&self) -> U128;
pub fn ft_balance_of(&self, account_id: AccountId) -> U128;
pub fn ft_metadata(&self) -> FungibleTokenMetadata;

pub fn storage_balance_of(&self, account_id: AccountId) -> Option<StorageBalance>;

pub fn new(owner_id: AccountId) -> Self;

pub fn upgrade_name_symbol(&mut self, name: String, symbol: String);
pub fn upgrade_icon(&mut self, data: String);
pub fn add_to_blacklist(&mut self, account_id: &AccountId);
pub fn remove_from_blacklist(&mut self, account_id: &AccountId);
pub fn destroy_black_funds(&mut self, account_id: &AccountId);
pub fn pause(&mut self);
pub fn resume(&mut self);
pub fn set_fixed_spread(&mut self, spread: U128) {
pub fn set_adaptive_spread(&mut self, params: Option<ExponentialSpreadParams>);
pub fn set_owner(&mut self, owner_id: AccountId);
pub fn extend_guardians(&mut self, guardians: Vec<AccountId>);
pub fn remove_guardians(&mut self, guardians: Vec<AccountId>);

pub fn upgrade();
pub fn migrate() -> Self;