This subroutine will write out a string to the specified file.
String - This is the string you wish to write out to your file.
FileName - This is the file name that you wish to write the string to.
These are actual examples from the Aneuch source code:
Prior to this line being called, @files was populated via the ListAllPages API. The sub then writes out that list of files to the file $DataDir/pageindex.