def METHOD_NAME(self):
    # Put more-specific prefixes first
    check_prefixes = [
        join_path(self.prefix, "share", "tk{0}".format(self.version.up_to(2))),
        self.prefix,
    ]
    for prefix in check_prefixes:
        result = find_first(prefix, "tk.tcl")
        if result:
            return os.path.dirname(result)
    raise RuntimeError("Cannot locate tk.tcl")