Suppose we want to tell Cassie that a dog bit John, without telling her
which dog (it might not matter which, or we might not know). We'll do
this in two steps. First, we'll tell Cassie that something is a dog;
then we'll tell her that the dog bit John. The first can
be done by creating a Skolem constant representing a dog.
The way to do this in SNePSUL is by prefixing a # to
a SNePSUL variable
(UM§2.7), e.g., #dog.