Function call or variable?

[lhuynh@siam.ICS.UCI.EDU (Thomas Huynh)]

Given that the following lines are the only code in the
module, how can one determine if the identifier "func_or_var"
is a function call or variable?  Is it possible
to come any conclusion at all?  Assume that the identifier
"func_or_var" is defined in another module.

-- File starts here
with This_System;
use This_System;

procedure Validate(a, b : in out integer) is
begin
  if (func_or_var)
    a := b;
  end if;
end Validate;
-- End of file