def METHOD_NAME(self, env, dependent_spec):
    """Set TCL_LIBRARY to the directory containing init.tcl.
    Set TCLLIBPATH to include the tcl-shipped directory for
    extensions and any other tcl extension it depends on.
    For further info see:
    * https://wiki.tcl-lang.org/page/TCL_LIBRARY
    * https://wiki.tcl-lang.org/page/TCLLIBPATH
    """
    env.set('TCL_LIBRARY', self._find_script_dir())
        #sorted(find(self.prefix, 'init.tcl'))[0]))
    # If we set TCLLIBPATH, we must also ensure that the corresponding
    # tcl is found in the build environment. This to prevent cases
    # where a system provided tcl is run against the standard libraries
    # of a Spack built tcl. See issue #7128 that relates to python but
    # it boils down to the same situation we have here.
    if not is_system_path(self.prefix.bin):
        env.prepend_path('PATH', self.prefix.bin)
    # WARNING: paths in $TCLLIBPATH must be *space* separated,
    # its value is meant to be a Tcl list, *not* an env list
    # as explained here: https://wiki.tcl-lang.org/page/TCLLIBPATH:
    # "TCLLIBPATH is a Tcl list, not some platform-specific
    # colon-separated or semi-colon separated format"
    # WARNING: Tcl and Tcl extensions like Tk install their configuration files
    # in subdirectories like `<prefix>/lib/tcl8.6`. However, Tcl is aware of this,
    # and $TCLLIBPATH should only contain `<prefix>/lib`. $TCLLIBPATH is only needed
    # because we install Tcl extensions to different directories than Tcl. See:
    # https://core.tcl-lang.org/tk/tktview/447bd3e4abe17452d19a80e6840dcc8a2603fcbc
    env.prepend_path(
        'TCLLIBPATH', self.spec['tcl'].libs.directories[0], separator=' ')
    for d in dependent_spec.traverse(deptype=('build', 'run', 'test')):
        if d.package.extends(self.spec):
            # Tcl libraries may be installed in lib or lib64, see #19546
            for lib in ['lib', 'lib64']:
                tcllibpath = join_path(d.prefix, lib)
                if os.path.exists(tcllibpath):
                    env.prepend_path('TCLLIBPATH', tcllibpath, separator=' ')