"\" for prefix \"" $prefix \"...]
    }

    return $result
  }

  #
  # NOTE: This procedure creates a new interpreter, which may be "safe", and
  #       places a reference to it in a variable in the context of the caller
  #       identified by the varName argument.  The created interpreter has a
  #       fully functioning [package] command ensemble; all other commands do
  #       nothing and return nothing.  This procedure may raise script errors.
  #
  proc createInterp { varName } {
    upvar 1 $varName interp

    set interp [interp create -safe]
    interp eval $interp [list set dir .]

    }

    interp eval $interp [list proc proc args ""]; # NOP
    return ""
  }

  #
  # NOTE: This procedure evaluates a script file and attempts to determine the
  #       list of new [package ifneeded] scripts added by it.  When successful
  #       it returns a list-of-lists.  Each element of the outer list contains
  #       a package name and the list of its versions in descending order; in
  #       the event of failure, empty lists may be returned for the outer list
  #       or for a list of versions.  The interp argument is the interp to use
  #       when evaluating the file specified by the fileName argument.  This
  #       procedure may raise script errors.
  #
  proc getIfNeededVersions { interp fileName } {
    set result [list]

    set oldPackageNames [interp eval $interp [list package names]]
    interp invokehidden $interp source $fileName; # [package ifneeded], etc.
    set newPackageNames [interp eval $interp [list package names]]