Sample Contract for Space Missions

Coin.sol

pragma solidity >=0.5.0 <0.7.0;

contract Coin {
    string public name; //publicly accessible name paratmer
    string public symbol; //publicly accessible symbol parameter

    mapping (address => uint) private balances; //creates a "table" for matching address to token balance
    
    event Transfer(address indexed _from, address indexed _to, uint256 _value); //emits a standard ERC-20 Transfer event

    // function that is called when the smart contract is deployed (sets up the parameters)
    constructor() public {
        name = "aalu1418"; //set token name to Discord name
        symbol = "TEST"; // set token symbol
        
        balances[msg.sender] = 10e18; //mint initial balance
    }

    //transfer tokens from function caller to address
    function transfer(address receiver, uint amount) public returns(bool) {
        require(amount <= balances[msg.sender], "Insufficient balance.");
        balances[msg.sender] -= amount;
        balances[receiver] += amount;
        emit Transfer(msg.sender, receiver, amount);
        
        return true;
    }
    
    //get balance of address
    function balanceOf(address tokenOwner) public view returns(uint balance){
      return balances[tokenOwner];
    }
}