  We present setups for the practical realization of adding control to unknown
subroutines, supplementing the existing quantum optical scheme for black-box
control with a counterpart for the quantum control of the ordering of sequences
of operations. We also provide schemes to realize either task using trapped
ions. These practical circumventions of recent no-go theorems are based on
existing technologies. We argue that the possibility to add control to unknown
operations in practice is a common feature of many physical systems. Based on
the proposed implementations we discuss the apparent contradictions between
theory and practice.
