foreach

* desc
Loops for each element in _from_ over its substatements. In particular, it stores in the beginning the elements from the _from_ set, then it runs the loop once for each element and makes this element available in _into_ during the loop. After the last loop, _into_ remains unchanged.

* properties
exec:yes
ret_set:
control_flow:yes

* substatements
exec:

* depending_on
input = set:from

* changes
output = set:into
(There also might be changes by the substatements to other sets)

* time
(time_of_substatements * set:into)

* space
set:from
