lib/less/parser/parser.js
function () {
                var entities = [], e, delim, index = parserInput.i;

                do {
                    e = this.comment();
                    if (e) {
                        entities.push(e);
                        continue;
                    }
                    e = this.addition() || this.entity();
                    if (e) {
                        entities.push(e);
                        // operations do not allow keyword "/" dimension (e.g. small/20px) so we support that here
                        if (!parserInput.peek(/^\/[\/*]/)) {
                            delim = parserInput.$char('/');
                            if (delim) {
                                entities.push(new(tree.Anonymous)(delim, index));
                            }
                        }
                    }
                } while (e);
                if (entities.length > 0) {
                    return new(tree.Expression)(entities);
                }
            }
function () {
                var entities = [], e, delim, index = parserInput.i;

                do {
                    e = this.comment();
                    if (e) {
                        entities.push(e);
                        continue;
                    }
                    e = this.addition() || this.entity();
                    if (e) {
                        entities.push(e);
                        // operations do not allow keyword "/" dimension (e.g. small/20px) so we support that here
                        if (!parserInput.peek(/^\/[\/*]/)) {
                            delim = parserInput.$char('/');
                            if (delim) {
                                entities.push(new(tree.Anonymous)(delim, index));
                            }
                        }
                    }
                } while (e);
                if (entities.length > 0) {
                    return new(tree.Expression)(entities);
                }
            }
function ( ) { var entities = [ ] , e , delim , index = parserInput . i ; do { e = this . comment ( ) ; if ( e ) { entities . push ( e ) ; continue ; } e = this . addition ( ) || this . entity ( ) ; if ( e ) { entities . push ( e ) ; // operations do not allow keyword "/" dimension (e.g. small/20px) so we support that here if ( ! parserInput . peek ( / ^\/[\/*] / ) ) { delim = parserInput . $char ( '/' ) ; if ( delim ) { entities . push ( new ( tree . Anonymous ) ( delim , index ) ) ; } } } } while ( e ) ; if ( entities . length > 0 ) { return new ( tree . Expression ) ( entities ) ; } }
Expressions either represent mathematical operations, or white-space delimited Entities.  1px solid black @var * 2
Expressions either represent mathematical operations or white - space delimited Entities . 1px solid black