Similar to deffacts, the definstances construct allows the specification of
instances which will be created every time the reset command is executed.
On every reset all current instances receive a delete message, and the
equivalent of a make-instance function call is made for every instance
specified in definstances constructs.
The syntax of the definstances construct is:
<definstances-construct>
::= (definstances <definstances-name> [<comment>]
<instance-template>*)
<instance-template> ::= (<instance-definition>)
<instance-definition> ::= <instance-name-expression> of
<class-name-expression>
<slot-override>*
<slot-override> ::= (<slot-name-expression> <expression>*)