A function prototype is a definition that is used to perform type checking on function calls when the EGL system code does not have access to the function itself.
A function prototype begins with the keyword function, then lists the function name, its parameters (if any), and return value (if any). The prototype includes no executable code.
A Delegate part conveys the same general information that a function prototype does, but in a different form (see Delegate part).
ExternalType TaxModule type JavaObject
// Define public variables
adjustedGrossIncome FLOAT;
companyName STRING;
// Define function prototype
function calculateTax (adjIncome FLOAT) returns (FLOAT);
// Define constructor prototype
constructor (taxAuthority STRING);
end