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// www.medium.com/@0xsuzume
// https://twitter.com/s_shitakiri
// SPDX-License-Identifier: MIT
pragma solidity >=0.6.0 <0.9.0;
abstract contract Context {
    function _msgSender() internal view returns (address payable) {
        return payable(msg.sender);
    }
    function _msgData() internal view returns (bytes memory) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        return msg.data;
    }
}
/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20Upgradeable {
    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);
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