How to use the pkgconfig.package function in pkgconfig

def _pkgconfig_check(self, test):
        # Hack to by pass pkgconfig checks when just wanting to download the
        # source.
        if self.macros['_dry_run'] == '1' and \
           ('with_download' in self.macros and self.macros['with_download'] == '1'):
            return '0'
        ok = False
        log.trace('pkgconfig: check: crossc=%d pkg_crossc=%d prefix=%s' % ( self._cross_compile(),
                                                                            self.pkgconfig_crosscompile,
                                                                            self.pkgconfig_prefix))
        log.trace('pkgconfig: check: test=%s' % (test))
        if type(test) == str:
            test = test.split()
        if not self._cross_compile() or self.pkgconfig_crosscompile:
            try:
                pkg = pkgconfig.package(test[0],
                                        prefix = self.pkgconfig_prefix,
                                        output = self._output,
                                        src = log.trace)
                if len(test) != 1 and len(test) != 3:
                    self._error('malformed check: %s' % (' '.join(test)))
                else:
                    op = '>='
                    ver = '0'
                    if len(test) == 3:
                        op = test[1]
                        ver = self.macros.expand(test[2])
                    ok = pkg.check(op, ver)
            except pkgconfig.error as pe:
                self._error('pkgconfig: check: %s' % (pe))
            except:
                raise error.internal('pkgconfig failure')

def _pkgconfig_flags(self, package, flags):
        pkg_flags = None
        if not self._cross_compile() or self.pkgconfig_crosscompile:
            try:
                pkg = pkgconfig.package(package,
                                        prefix = self.pkgconfig_prefix,
                                        output = self._output,
                                        src = log.trace)
                pkg_flags = pkg.get(flags)
                if pkg_flags and self.pkgconfig_filter_flags:
                    fflags = []
                    for f in pkg_flags.split():
                        if not f.startswith('-W'):
                            fflags += [f]
                    pkg_flags = ' '.join(fflags)
                log.trace('pkgconfig: %s:  %s' % (flags, pkg_flags))
            except pkgconfig.error as pe:
                self._error('pkgconfig: %s:  %s' % (flags, pe))
            except:
                raise error.internal('pkgconfig failure')
        if pkg_flags is None:

def _load_flags(conf, arch_bsp, path):
    if not os.path.exists(path):
        ctx.fatal('RTEMS path not found.')
    if os.path.exists(_pkgconfig_path(path)):
        pc = os.path.join(_pkgconfig_path(path), arch_bsp + '.pc')
        conf.to_log('Opening and load pkgconfig: ' + pc)
        pkg = pkgconfig.package(pc)
        config = None
    elif os.path.exists(os.path.join(path, 'rtems-config')):
        config = os.path.join(path, 'rtems-config')
        pkg = None
    flags = {}
    _log_header(conf)
    flags['CFLAGS'] = _load_flags_set('CFLAGS', arch_bsp, conf, config, pkg)
    flags['LDFLAGS'] = _load_flags_set('LDFLAGS', arch_bsp, conf, config, pkg)
    flags['LIB'] = _load_flags_set('LIB', arch_bsp, conf, config, pkg)
    return flags