src/parser.js
function(){
        var node = this.parseAdd();
        while(this.skipValue(lexer.TOKEN_TILDE, '~')) {
            var node2 = this.parseAdd();
            node = new nodes.Concat(node.lineno,
                                 node.colno,
                                 node,
                                 node2);
        }
        return node;
    }
function(){
        var node = this.parseAdd();
        while(this.skipValue(lexer.TOKEN_TILDE, '~')) {
            var node2 = this.parseAdd();
            node = new nodes.Concat(node.lineno,
                                 node.colno,
                                 node,
                                 node2);
        }
        return node;
    }
function ( ) { var node = this . parseAdd ( ) ; while ( this . skipValue ( lexer . TOKEN_TILDE , '~' ) ) { var node2 = this . parseAdd ( ) ; node = new nodes . Concat ( node . lineno , node . colno , node , node2 ) ; } return node ; }
finds the '~' for string concatenation
finds the ~ for string concatenation