This function returns a list of the contents of SMAP data files.
list_smap(files, all = TRUE)A data.frame produced by download_smap() that
specifies input data files.
If TRUE a longer, more detailed list of information on each entry is provided.
Returns a list of data.frame objects that list the contents
of each data file in files.
if (FALSE) {
files <- find_smap(id = "SPL4SMGP", dates = "2015-03-31", version = 4)
files <- download_smap(files[1, ])
list_smap(files)
list_smap(files, all = TRUE)
}