#       persisting them for subsequent uses by the target language.
  #       The language argument must be one of the literal strings "eagle",
  #       "tcl", or "client".  The version argument must be one of the
  #       literal strings "8.4", "8.5", or "8.6" when the language is "tcl"
  #       -OR- the literal string "1.0" when the language is either "eagle"
  #       or "client".  The platform argument must be an empty string -OR-
  #       one of the literal strings "msil" or "neutral", or one of the values
  #       returned by the [getPlatform] procedure..  An empty string means
  #       that the associated package does not require a specific platform.
  #       The fileNames argument must be a well-formed list of file names to
  #       download, each one relative to the language and version-specific
  #       directory on the package file server.  The options argument must
  #       be a dictionary of name/value pairs.  The -persistent option should
  #       be non-zero if the downloaded files should be saved to permanent
  #       storage for subsequent use.  The -usePgp option should be non-zero