Exercise 3.44: Consider the problem of
transferring an amount from one account to another.  Ben Bitdiddle claims that
this can be accomplished with the following procedure, even if there are
multiple people concurrently transferring money among multiple accounts, using
any account mechanism that serializes deposit and withdrawal transactions, for
example, the version of make-account in the text above.


(define 
  (transfer from-account to-account amount)
  ((from-account 'withdraw) amount)
  ((to-account 'deposit) amount))

Louis Reasoner claims that there is a problem here, and that we need to use a
more sophisticated method, such as the one required for dealing with the
exchange problem.  Is Louis right?  If not, what is the essential difference
between the transfer problem and the exchange problem?  (You should assume that
the balance in from-account is at least amount.)