original_string: public function validateLuhn($input)
      {
          $checksum = '';
          foreach (str_split(strrev($input)) as $i => $d) {
              $checksum .= ($i %2 !== 0) ? ($d * 2) : $d;
          }
          return array_sum(str_split($checksum)) % 10 === 0;
      }
code: public function validateLuhn($input)
      {
          $checksum = '';
          foreach (str_split(strrev($input)) as $i => $d) {
              $checksum .= ($i %2 !== 0) ? ($d * 2) : $d;
          }
          return array_sum(str_split($checksum)) % 10 === 0;
      }
code_tokens: public function validateLuhn ( $ input ) { $ checksum = '' ; foreach ( str_split ( strrev ( $ input ) ) as $ i => $ d ) { $ checksum .= ( $ i % 2 !== 0 ) ? ( $ d * 2 ) : $ d ; } return array_sum ( str_split ( $ checksum ) ) % 10 === 0 ; }
docstring: Check if the input is valid luhn number
  
  @param string $input
  @return bool
  @link https://gist.github.com/troelskn/1287893
docstring_tokens: Check if the input is valid luhn number