👉 A left in mathematics refers to the set of all elements that are less than or equal to a given value. For example, if we have a list of numbers and we want to find out which ones are less than 5, we can use a function like `min()` to determine this. ```python def find_lefts(nums): return [num for num in nums if num <= 5] ``` In the above code snippet, `nums` is a list of numbers.