lrange
lrange <list> <start index> <end index>
This function returns a range of Efinity Tcl objects from the collection
based on the range of index values. end is the index value of the last
element. In the following example, the end-2 index is the third element
from the end.
# Return the first three elements of a collection
set elements [lrange [get_cells *~FF] 0 2]
# Return the last three elements of a collection
set elements [ lrange [ get_cells *~FF] end-2 end]