function transformTokens(tokens, camelCase) {
  switch (camelCase) {
  case true:
    return reduce(tokens, camelizeKeys, assign({}, tokens));

  case 'dashes':
    return reduce(tokens, camelizeDashedKeys, assign({}, tokens));

  case 'dashesOnly':
    return reduce(tokens, camelizeOnlyDashedKeys, {});

  case 'only':
    return reduce(tokens, camelizeOnlyKeys, {});
  }

  return tokens;
}
@param  {object} tokens
@param  {boolean|string} camelCase 'dashes|dashesOnly|only'
@return {object}