\begin{tikzpicture}

\begin{tikzpicture}
\begin{object}[text width=6cm]{Thomas' account}{0,0}
\instanceOf{BankAccount}
\attribute{owner = Thomas}
\attribute{balance = 100}

\operation{deposit(amount : Dollars)}
\operation[0]{withdrawl(amount : Dollars)}
\end{object}
\end{tikzpicture}