The next function we visit is find-symbol.  This is used to determine whether a particular package has a named symbol, and whether that symbol is internal, external, or inherited from another package.

I would recommend that you review the for thorough discussion of what a Lisp package is, under its own article.  A package in Lisp has qualities that a C++ programmer would look at as something like a cross between namespaces and classes.

The find-symbol function allows the user to query a package to discover whether a particular name is a symbol in the package, and if so, whether it is internal to the package, external to the package, or derived from an ancestor package.  This can be helpful, for example, in designing work-arounds for different versions of a library, by probing for functions not present in all versions of the package.