What should be the argument's type if it is a function?

edit

The argument's type of a function will depend on the specific requirements of the function and the inputs it expects to receive. In many cases, the argument's type may be specified as a specific data type such as a number, string, or boolean. However, in some cases, the argument's type may be more complex, such as an array, object, or custom data type. Ultimately, the argument's type should be designed to ensure that the function can accurately process the inputs it receives and return the expected output.