'Call a stored database procedure with the given name.
The sequence of parameters must contain one entry for each argument that the procedure expects.
The result of the call is returned as modified copy of the input sequence.
Input parameters are left untouched, output and input/output parameters replaced
with possibly new values.
The procedure may also provide a result set as output, which is
then available through the standard fetchXXX() methods.'

def callproc(self, procname, parameters=None):

    self.messages = []
    return self._executeHelper(procname, True, parameters)
