Built-in functions are used in the following contexts: 1.
To call a built-on function to obtain a value.
To invoke a built and/or built-off function.
To change the value of a built function.
To set a built in function to the specified value.
To return a built on function from a builtin function.
To execute a builton function in an external process.
To write to a file and/ or to the standard output.
To read from a file.
To run a builtoff function in a builtout process.
To create a function that can be used by another builtin.
To define a function to be used as a parameter in a call to a built builtin operation.
To assign a function a value to a parameter.
To specify a function as a global variable in an expression.
To access the contents of a file that has been written to using a built out process.