code: public function getAttribute($strKey)
  	{
  		if (!isset($this->arrAttributes[$strKey]))
  		{
  			return '';
  		}
  
  		$varValue = $this->arrAttributes[$strKey];
  
  		// Prevent the autofocus attribute from being added multiple times (see #8281)
  		if ($strKey == 'autofocus')
  		{
  			unset($this->arrAttributes[$strKey]);
  		}
  
  		if ($strKey == 'disabled' || $strKey == 'readonly' || $strKey == 'required' || $strKey == 'autofocus' || $strKey == 'multiple')
  		{
  			return ' ' . $strKey;
  		}
  		elseif ($varValue != '')
  		{
  			return ' ' . $strKey . '="' . StringUtil::specialchars($varValue) . '"';
  		}
  
  		return '';
  	}
docs: Return a single attribute
  
  @param string $strKey The attribute name
  
  @return string The attribute markup