<expr0> "[" <expr1> "]"This form is just a shorthand for an invocation of a fetch method and is equivalent to
<expr0> "." "fetch" "(" <expr1> ")"
The expression is legal whenever the corresponding invocation is
legal. In other words, the type of expr0 must define a
procedure method named "fetch" with a single argument whose type is a
supertype of expr1. For example, if "a" is an array of
integers, "a[27]" is equivalent to the invocation "a.fetch(27)".
[usage761]