General Thread for practicing question formatting

[maoxue0126]

[SALegend]

well done

[omarhibshi]

I love the course

[IamQua]

function fund() public payable {
        require(msg.value.getConversionRate() >= MINIMUM_USD, "You need to spend more ETH!");
        // require(PriceConverter.getConversionRate(msg.value) >= MINIMUM_USD, "You need to spend more ETH!");
        addressToAmountFunded[msg.sender] += msg.value;
        funders.push(msg.sender);
    }

Errorizing:

TypeError: "msg.value" and "callvalue()" can only be used in payable public functions. 

Help?