$ clisp

<...snip...>

[1]> (load "heron.l")
;; Loading file heron.l ...
;; Loaded file heron.l
T
[2]> (heron 4.7 6.6 9.2)
14.765548
[3]> (heron 21.21 32.32 410)
#C(0 41649.977)
[4]> (bye)
Bye.