By default, a list of length(h3_address). Each list element
contains a character vector of H3 cells belonging to that step away from
the input address.
Arguments
h3_address
Character; 15-character cell index generated by H3.
ring_size
Character; number of steps away from the central cell.
Defaults to 1.
simple
Logical; whether to return a vector of outputs or a data frame
containing both inputs and outputs.