How to use the grommet-icons.FacebookOption function in grommet-icons

'System Status'
  ), _react2.default.createElement(
    StyledNavListItem,
    { href: 'https://www.zooniverse.org/security' },
    'Security'
  )],
  projectNavList: [_react2.default.createElement(
    StyledNavListHeader,
    { href: 'https://www.zooniverse.org/projects' },
    'Projects'
  )],
  smallSectionColorIndex: '#eef2f5',
  socialNavList: [_react2.default.createElement(
    StyledNavListItem,
    { className: 'social-media', href: 'https://www.facebook.com/therealzooniverse', a11yTitle: 'Facebook' },
    _react2.default.createElement(_grommetIcons.FacebookOption, { colorIndex: 'brand', size: 'small' }),
    ' '
  ), _react2.default.createElement(
    StyledNavListItem,
    { className: 'social-media', href: 'https://twitter.com/the_zooniverse', a11yTitle: 'Twitter' },
    _react2.default.createElement(_grommetIcons.Twitter, { colorIndex: 'brand', size: 'small' })
  ), _react2.default.createElement(
    StyledNavListItem,
    { className: 'social-media', href: 'https://www.instagram.com/the.zooniverse/', a11yTitle: 'Instagram' },
    _react2.default.createElement(_grommetIcons.Instagram, { colorIndex: 'brand', size: 'small' })
  )],
  talkNavList: [_react2.default.createElement(
    StyledNavListHeader,
    { href: 'https://www.zooniverse.org/talk' },
    'Talk'
  )],
  zooTagline: 'People-Powered Research'

function SocialAnchor(_ref) {
  var colorTheme = _ref.colorTheme,
      hrefs = _ref.hrefs,
      service = _ref.service;

  var icons = {
    facebook: _react2.default.createElement(_grommetIcons.FacebookOption, { size: 'small' }),
    instagram: _react2.default.createElement(_grommetIcons.Instagram, { size: 'small' }),
    twitter: _react2.default.createElement(_grommetIcons.Twitter, { size: 'small' })
  };

  return _react2.default.createElement(
    _styledComponents.ThemeProvider,
    { theme: { mode: colorTheme } },
    _react2.default.createElement(StyledSocialAnchor, {
      href: hrefs[service],
      a11yTitle: service,
      icon: icons[service]
    })
  );
}