books/axiom.sty add \sig and \bfref

     \sig{foo}{(String,Integer)}{Boolean}
will generate an Axiom-like signature line, e.g.
     foo : (String,Integer) -> Boolean
in the pdf

     \bfref{foo}
generates an inline link to the function definition
which is useful in explanations. e.g.
     foo (4.3)
where 'foo' is in bold font and 4.3 is a hyperlink.