public function process(PHP_CodeSniffer_File $phpcsFile, $stackPtr) {
$tokens = $phpcsFile
->getTokens();
if ($tokens[$stackPtr - 1]['code'] !== T_WHITESPACE || $tokens[$stackPtr + 1]['code'] !== T_WHITESPACE) {
$phpcsFile
->addError('Concatenation operator must be surrounded by whitespace', $stackPtr);
}
}