// This contract is part of Zellic’s smart contract dataset, which is a collection of publicly available contract code gathered as of March 2023.

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.5.0) (token/ERC20/IERC20.sol)

pragma solidity ^0.8.9;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    // OPTIONAL public state variable getter is automatically generated.
    // function name() public view returns (string);
    // function symbol() public view returns (uint8);
    // function decimals() public view returns (uint256);

    /**
     * @return The amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @param account ? caller msg.sender ?
     * @return The amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev This is zero by default.
     * This value changes when {approve} or {transferFrom} are called.
     *
     * @return The remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Moves `amount` tokens from the caller's account to `to`.
     *
     * Emits a {Transfer} event.
     *
     * @return A boolean value indicating whether the operation succeeded.
     */
    function transfer(address to, uint256 amount) external returns (bool);

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Emits an {Approval} event.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * @return A boolean value indicating whether the operation succeeded.
     */
    function approve(address spender, uint256 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `from` to `to` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Emits a {Transfer} event.
     *
     * @return A boolean value indicating whether the operation succeeded.
     */
    function transferFrom(
        address from,
        address to,
        uint256 amount
    ) external returns (bool);

    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}.
     * `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);
}