$inst->directories(module[,string[,dir[,...]]])
Returns list of directories. Only returns directories that contain files from the specified module. Parameters are:
Required. The name of a module; returns a list of all directories in the package.
Optional. Possible values are prog, man, or all to
return program directories, manual directories, or all directories,
respectively.
Optional. One or more directories. If specified, only directories under the specified directories are returned.