original_string: public static function getHeader($header, $default = null)
      {
          $header  = strtolower($header);
          $headers = self::getInstance()->getHeaders();
          $headers = array_change_key_case($headers, CASE_LOWER);
          if (array_key_exists($header, $headers)) {
              $value = \is_array($headers[$header]) ? implode(', ', $headers[$header]) : $headers[$header];
              return $value;
          }
          return $default;
      }
code: public static function getHeader($header, $default = null)
      {
          $header  = strtolower($header);
          $headers = self::getInstance()->getHeaders();
          $headers = array_change_key_case($headers, CASE_LOWER);
          if (array_key_exists($header, $headers)) {
              $value = \is_array($headers[$header]) ? implode(', ', $headers[$header]) : $headers[$header];
              return $value;
          }
          return $default;
      }
code_tokens: public static function getHeader ( $ header , $ default = null ) { $ header = strtolower ( $ header ) ; $ headers = self :: getInstance ( ) -> getHeaders ( ) ; $ headers = array_change_key_case ( $ headers , CASE_LOWER ) ; if ( array_key_exists ( $ header , $ headers ) ) { $ value = \ is_array ( $ headers [ $ header ] ) ? implode ( ', ' , $ headers [ $ header ] ) : $ headers [ $ header ] ; return $ value ; } return $ default ; }
docstring: Search for a header value
  
  @param string $header
  @param mixed  $default
  
  @return string
docstring_tokens: Search for a header value