.he 'MISHAP050''Page %'
.fo 'Aaron Sloman'- % -'January 1978'
ERROR 50 	Attempt to apply a non function
.br
When you type HD([1 2 3]) you are applying the function
HD to the list [1 2 3]. If you try to apply a non-function,
e.g. as a result of mistyping, you get an error. Try
 	: head([1 2 3]) =>
.br
Notice that the culprits help you by giving both the name
of the variable whose value was expected to be a
function, and the actual value found.
