Dependencies: making sure your ado/do-files run in any computer

Imagine that you write a do-file or an ado-file in which you use one or serveral user-written commands available in SSC (or any other repository). However, when you share it with someone else, that person is constantly frustrated because your code is constantly requesting the use of a command that has not been installed in their computers. You could solve your problem by always adding the following code at the beginning of do/ado-file.