Functions in expressions

[Phil Longstaff]

One place that guile/gh (now deprecated) is used is in the expression parser.  
If a function a is used (e.g. "10+f(20)"), then it evaluates "gnc:f" as a 
scheme function and calls it with the specified arguments.

Are there any defined functions in the scheme code that are set up to be used 
this way?

I think it's fairly simple to replace the deprecated gh_xxx() call with 
scm_yyy() calls, but I want to test.

Phil