When evaluating each row of a data frame in matsindf_apply(),
the result will be a tibble with list columns.
This function tells whether a column can be unlisted.
This is internal helper function and should not be called externally.
should_unlist(this_col)A boolean. TRUE if the column can be unlisted, FALSE otherwise.
When this_col is a data.frame, a named boolean vector,
one entry for each column.
The column to be checked.
Or a data.frame, in which case every column is checked.