This function is intended to be convert any R object to a short descriptive string,
The following rules apply:
atomic() with length 0 or 1: printed as-is.
atomic() with length greater than 1,
x is collapsed with
and the resulting string is truncated to
x is an expression: converted to character.
Otherwise: the class is printed.
x is a list, the above rules are applied (non-recursively) to its elements.
as_short_string(x, width = 30L, num_format = "%.4g")
as_short_string(list(a = 1, b = NULL, "foo", c = 1:10))#>  "a=1, b=<NULL>, <unnamed>=foo, c=1,2,3,4,5,6,7,8,9,10"