Throughout this manual, the syntax for new forms is described using a
pattern notation with ellipses. Plain, centered ellipses ( 
)
indicate zero or more repetitions of the preceding
S-expression. Ellipses with a ``1'' subscript ( 
) indicate
one or more repetitions of the preceding S-expression. For example:
(random-branch
(name expr
)
)
The first set of ellipses indicate that any number of exprs (or
none) can follow the name part of the expression. The second set
of ellipses indicate that a random-branch expression can contain
any number of (name expr ) clauses, as long as
at least one clause is present. In describing parts of the
random-branch syntax, the name expr refers to a single
sub-expression in a random-branch expression.