ucture.  To each place where an identifier is bound in a program
there corresponds a <a name="%_idx_36"></a><em>region</em> of the program text within which
the binding is visible.  The region is determined by the particular
binding construct that establishes the binding; if the binding is
established by a <tt>lambda</tt> expression, for example, then its region
is the entire <tt>lambda</tt> expression.  Every mention of an identifier
refers to the binding of the identifier that established the
innermost of