This program demonstrates the old trick that had to be used before the operator ByVal was introduced.
Example trick.bas :
#! /usr/bin/scriba
print " "
a=1
call f(a+0)
print a
print
call f(a)
print a
print
function f(x)
x=x+1
end function
Result executing trick.bas :
Possible error messages sent to stderr: