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@section History and Implementation of SBCL
-You can work productively with SBCL without knowing anything
+You can work productively with SBCL without knowing or
understanding anything about where it came from, how it is
implemented, or how it extends the ANSI Common Lisp standard. However,
a little knowledge can be helpful in order to understand error
to the casual user, since SBCL still can and does execute code
interactively by compiling it on the fly. (It is visible if you know how
to look, like using @code{compiled-function-p}; and it is visible in the
-way that that SBCL doesn't have many bugs which behave differently in
+way that SBCL doesn't have many bugs which behave differently in
interpreted code than in compiled code.) What it means is that in SBCL,
the @code{eval} function only truly ``interprets'' a few easy kinds of
forms, such as symbols which are @code{boundp}. More complicated forms