static addBinaryOp(op_name, precedence, isRightAssociative) {
		Jsep.max_binop_len = Math.max(op_name.length, Jsep.max_binop_len);
		Jsep.binary_ops[op_name] = precedence;
		if (isRightAssociative) {
			Jsep.right_associative.add(op_name);
		}
		else {
			Jsep.right_associative.delete(op_name);
		}
		return Jsep;
	}
@method jsep.addBinaryOp
@param {string} op_name The name of the binary op to add
@param {number} precedence The precedence of the binary op (can be a float). Higher number = higher precedence
@param {boolean} [isRightAssociative=false] whether operator is right-associative
@returns {Jsep}