Like rapply, recursive_apply is a recursive
version lapply but contrary to
rapply, recursive_apply does not ignore
NULL values. Each element of the list which is not itself
a list is replaced by the result of applying fn. If down the line
there are data.frames, then their class is preserved.
recursive_apply(x, fn)A list whose non-list elements have been replaced by the result of
applying fn.
A list (of potentially many nested lists).
A function of a single argument.