lib/less/parser/parser.js
function () {
                var entities = this.entities, negate;

                if (parserInput.peek(/^-[@\$\(]/)) {
                    negate = parserInput.$char('-');
                }

                var o = this.sub() || entities.dimension() ||
                        entities.color() || entities.variable() ||
                        entities.property() || entities.call() ||
                        entities.quoted(true) || entities.colorKeyword() ||
                        entities.mixinLookup();

                if (negate) {
                    o.parensInOp = true;
                    o = new(tree.Negative)(o);
                }

                return o;
            }
function () {
                var entities = this.entities, negate;

                if (parserInput.peek(/^-[@\$\(]/)) {
                    negate = parserInput.$char('-');
                }

                var o = this.sub() || entities.dimension() ||
                        entities.color() || entities.variable() ||
                        entities.property() || entities.call() ||
                        entities.quoted(true) || entities.colorKeyword() ||
                        entities.mixinLookup();

                if (negate) {
                    o.parensInOp = true;
                    o = new(tree.Negative)(o);
                }

                return o;
            }
function ( ) { var entities = this . entities , negate ; if ( parserInput . peek ( / ^-[@\$\(] / ) ) { negate = parserInput . $char ( '-' ) ; } var o = this . sub ( ) || entities . dimension ( ) || entities . color ( ) || entities . variable ( ) || entities . property ( ) || entities . call ( ) || entities . quoted ( true ) || entities . colorKeyword ( ) || entities . mixinLookup ( ) ; if ( negate ) { o . parensInOp = true ; o = new ( tree . Negative ) ( o ) ; } return o ; }
An operand is anything that can be part of an operation, such as a Color, or a Variable
An operand is anything that can be part of an operation such as a Color or a Variable