function includesBothInAGroup(groups, left, right) {
	return groups.some(group => group.includes(left) && group.includes(right));
}
Checks whether any group which includes both given operator exists or not.
@param {Array<string[]>} groups A list of groups to check.
@param {string} left An operator.
@param {string} right Another operator.
@returns {boolean} `true` if such group existed.