For example, a function may take a single operand, transform it into a new data type, and return the result.
[1] While such usages bear a strong visual resemblance to identity functions, they create or alter a binary data value and thus change the program state.
During software development, null functions with the same names and type signatures as a planned functions are often used as stubs—that is, as non-functional placeholders that allow the incomplete body of code to be compiled and tested prior to completion of all planned features.
Null functions, particularly the NOP variety, are also used to provide delays of indeterminate length within wait loops.
A third use of null functions is as the definition of a program feature that, if created inadvertently, is almost always deleterious.