protected function partIdIsChildOfPart($partId, $parentPartId)
    {
        $parentPartId = $parentPartId.'.';
        return substr($partId, 0, strlen($parentPartId)) == $parentPartId;
    }
protected function partIdIsChildOfPart($partId, $parentPartId)
    {
        $parentPartId = $parentPartId.'.';
        return substr($partId, 0, strlen($parentPartId)) == $parentPartId;
    }
protected function partIdIsChildOfPart ( $ partId , $ parentPartId ) { $ parentPartId = $ parentPartId . '.' ; return substr ( $ partId , 0 , strlen ( $ parentPartId ) ) == $ parentPartId ; }
Checks whether a given part ID is a child of another part
eg. an RFC822 attachment may have one or more text parts

@param string $partId
@param string $parentPartId
@return bool
Checks whether a given part ID is a child of another part eg . an RFC822 attachment may have one or more text parts