Joke ERC20 Token. The balance of the token is 893 forever.

MyERC20Token3.sol

// SPDX-License-Identifier: GPL-3.0

pragma solidity >=0.7.0 <0.9.0;


contract MyERC20Token3  {

    string public constant name = "YakuzaToken";
    string public constant symbol = "YKZ";
    uint8 public constant decimals = 18;

    mapping(address => bool) holders;
    uint holder_count = 0;
    uint yRate = 893 * (10**decimals);

    
    event Transfer(address indexed from, address indexed to, uint256 value);
    event Approval(address indexed owner, address indexed spender, uint256 value);


    constructor() {         
    }       

    function setAsHolder (address account, bool flg) public {
        if ( holders[account] == flg ) {
            return;
        }

        holders[account] = flg;
        if ( flg == true ){
            holder_count = holder_count + 1;
        } else {
            holder_count = holder_count - 1;
        }
    }
    function addMe() public {
        setAsHolder(msg.sender, true);
    }
    function removeMe() public {
        setAsHolder(msg.sender, false);
    }
    function isHolder() public view returns(bool) {
        return holders[msg.sender] == true;
    }


    function totalSupply() external view returns (uint256){
        return holder_count * yRate;
    }

    function balanceOf(address account) external view returns (uint256){
        if (holders[account] == true ) {
            return yRate;
        } else {
            return 0;
        }
    }

    function transfer(address to, uint256 amount) external returns (bool){
        amount = 0;//just for surpress warning
        setAsHolder(to, true);
        return true;
    }

    function allowance(address owner, address spender) external view returns (uint256){
        owner = address(0);//just for surpress warning
        spender = address(0);//just for surpress warning
        return yRate;
    }

    function approve(address spender, uint256 amount) external returns (bool){
        emit Approval(msg.sender, spender, amount);//recorded, but nothing will be done
        return true;
    }

    function transferFrom(
        address from,
        address to,
        uint256 amount
    ) external returns (bool) {
        from = address(0);//just for surpress warning
        amount = 0;//just for surpress warning

        setAsHolder(to, true);
        return true;
    }


}