title: Solidity - Add Total Supply
body: <p>I'm learning solidity on <a href="https://remix.ethereum.org/" rel="nofollow noreferrer">remix</a>
  I'm also referencing this <a href="https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/token/ERC20/ERC20.sol" rel="nofollow noreferrer">open source</a> api for token creation.</p>
  <p>Right <a href="https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/token/ERC20/ERC20.sol#L92" rel="nofollow noreferrer">here</a> they provide a <code>_totalSupply()</code> function that I'd like to wire to my smart contract so it shows the total amount of tokens why I deploy it.</p>
  <p>What am doing wrong here?</p>
  <pre class="lang-js prettyprint-override"><code>pragma solidity ^0.8.0;
  
  import &quot;https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/token/ERC20/ERC20.sol&quot;;
  
  contract Foobar is ERC20 {
      constructor(uint256 initialSupply) public ERC20(&quot;Foobar&quot;, &quot;FOO&quot;) {
          _mint(msg.sender, initialSupply);
         // add totalSupply here
          _totalSupply(uint256 5000000000000000000000000000000000000000);
      }
  }
  </code></pre>