PR_ASSERT(cont->nchildren == 0);
MimeEncrypted_add_child (MimeObject *parent, MimeObject *child){  MimeContainer *cont = (MimeContainer *) parent;  PR_ASSERT(parent && child);  if (!parent || !child) return -1;  /* Encryption containers can only have one child. */  PR_ASSERT(cont->nchildren == 0);  if (cont->nchildren != 0) return -1;  return ((MimeContainerClass*)&MIME_SUPERCLASS)->add_child (parent, child);}