To create new columns (row entries) we always use DataFrame::withEntry(string $entryName, ScalarFunction|WindowFunction $ref) method.
We can create new entry by providing a unique $entryName, if the entry already exists it will be replaced.
As a second argument we can provide a static value or a function that will be evaluated for each row.
DataFrame::withEntry('number', lit(5))- creates a new column with a constant value of 5DataFrame::withEntry('is_odd', ref('another_column')->isOdd())- creates a new column that checks if the value ofanother_columnin is odd