'Ensure that the list of libraries is valid.
`library` is presumably provided as a command option \'libraries\'.
This method checks that it is a list of 2-tuples, where the tuples
are (library_name, build_info_dict).
Raise DistutilsSetupError if the structure is invalid anywhere;
just returns otherwise.'

def check_library_list(self, libraries):

    if (not isinstance(libraries, list)):
        raise DistutilsSetupError("'libraries'    option    must    be    a    list    of    tuples")
    for lib in libraries:
        if ((not isinstance(lib, tuple)) and (len(lib) != 2)):
            raise DistutilsSetupError("each    element    of    'libraries'    must    a    2-tuple")
        (name, build_info) = lib
        if (not isinstance(name, str)):
            raise DistutilsSetupError("first    element    of    each    tuple    in    'libraries'    must    be    a    string    (the    library    name)")
        if (('/' in name) or ((os.sep != '/') and (os.sep in name))):
            raise DistutilsSetupError(("bad    library    name    '%s':    may    not    contain    directory    separators" % lib[0]))
        if (not isinstance(build_info, dict)):
            raise DistutilsSetupError("second    element    of    each    tuple    in    'libraries'    must    be    a    dictionary    (build    info)")
