compile(token) { //
                const key = token.match[1].trim();
                const expression = token.match[2];
                // Compile the expression.
                const expressionStack = Twig.expression.compile.call(this, {
                    type: Twig.expression.type.expression,
                    value: expression
                }).stack;

                token.key = key;
                token.expression = expressionStack;

                delete token.match;
                return token;
            }
Set type logic tokens.

 Format: {% set key = expression %}