ild a tuple out of the topmost stack slice, after markobject.

      All the stack entries following the topmost markobject are placed into
      a single Python tuple, which single tuple object replaces all of the
      stack from the topmost markobject onward.  For example,

      Stack before: ... markobject 1 2 3 'abc'
      Stack after:  ... (1, 2, 3, 'abc')
      Z