Exercise 5.43: We argued in 4.1.6
that internal definitions for block structure should not be considered “real”
defines.  Rather, a procedure body should be interpreted as if the
internal variables being defined were installed as ordinary lambda
variables initialized to their correct values using set!.  
4.1.6 and Exercise 4.16 showed how to modify the metacircular
interpreter to accomplish this by scanning out internal definitions.  Modify
the compiler to perform the same transformation before it compiles a procedure
body.