Replace `\hole()` with `#hole`

[h0nzZik]

This:

syntax Pattern ::= Int
...
| "\\hole" "(" ")" [klabel(Phole)]

is a conceptual duplication of

syntax Variable ::= "#hole"

(from https://github.com/kframework/matching-logic-prover/blob/master/prover/lang/kore-lang.md)

[nishantjr]

Any reason that this is not a variable?
nevermind. I misunderstood

[xc93]

Adding this: rule #hole => \\hole()?

[nishantjr]

\hole() looks more like a symbol than a variable. I think replacing all instances of \hole() with #hole makes sense? We may need to change #hole to a set variable depending on how we use it of course

[h0nzZik]

I have been thinking of completely removing \hole() and use only #hole.