Can PHP functions be defined out of order similar to classes, and what considerations should be taken into account when doing so?

PHP functions can be defined out of order similarly to classes by using the function declaration syntax. However, it is important to note that functions must be defined before they are called in the code. To ensure that functions are defined in the correct order, it is recommended to define functions at the beginning of the file or use include statements to include files with function definitions before they are called.

// Define functions
function foo() {
    return "foo";
}

function bar() {
    return "bar";
}

// Call functions
echo foo();
echo bar();