function decompresses the compressed files contained in a .zip file. Compressed .zip files can be created using the compress
function or with other popular tools.
The argument zip_file_name is a string expression containing the file name of the .zip file. An optional string expression directory_name indicates the folder to which the files should be decompressed. If no directory name is specified, the files are decompressed to the current application directory.
The function returns the number of files (but not folders) decompressed from the .zip file. If there was an error decompressing files, the function returns default