The informal alternative is to treat the pattern as a cliche or idiom that will occur frequently in our writing of programs but will vary from use to use. When we want to write a new program, we remember writing or reading a similar one, go back and look at the first program, copy the relevant sections, and then modify them for the new program. If the borrowing is extensive, it would be good practice to insert a comment in the new program citing the original, but there would be no "official"

connection between the original and the derived program.