+ import std.math;
  import std.typecons;
- import std.math;
  /*
- 
-     Create a function that returns a tuple (a, b), where 'a' is
? ----

+ Create a function that returns a tuple (a, b), where 'a' is
-     the largest of negative integers, and 'b' is the smallest
? ----

+ the largest of negative integers, and 'b' is the smallest
-     of positive integers in an array.
? ----

+ of positive integers in an array.
-     If there is no negative or positive integers, return them as null.
? ----

+ If there is no negative or positive integers, return them as null.
- 
-     Examples:
? ----

+ Examples:
-     >>> largest_smallest_integers([2L, 4L, 1L, 3L, 5L, 7L])
? ----

+ >>> largest_smallest_integers([2L, 4L, 1L, 3L, 5L, 7L])
-     tuple(None, 1L)
? ----

+ tuple(None, 1L)
-     >>> largest_smallest_integers([])
? ----

+ >>> largest_smallest_integers([])
-     tuple(None, None)
? ----

+ tuple(None, None)
-     >>> largest_smallest_integers([0L])
? ----

+ >>> largest_smallest_integers([0L])
-     tuple(None, None)
? ----

+ tuple(None, None)
-     
  */
  Tuple!(Nullable!(long), Nullable!(long)) largest_smallest_integers(long[] lst)