Generate a function that accepts an arbitrarily deeply
nested list. Use flatten.at to set the
level of nestedness at which the flatterner will start to
flatten.
Usage
make_flattener(flatten.at = 1)
Arguments
flatten.at
An integer specifying the layer
after which to start the flattening. 1 means to
start at the very top.
Value
A function that can be used to flatten a nested list