The libraries under the (nausicaa parser-tools r6rs ---)
hierarchy provide tools to manipulate Scheme source code compliant with
the R6RS standard. It is suggested to import the libraries in this
hiearchy with r6. as prefix:
(import ---
(prefix (nausicaa parser-tools r6rs lexer) r6.)
(prefix (nausicaa parser-tools r6rs parser) r6.))