Abstract: Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for generating a sequence of commands from interconnected code blocks. In one aspect, a system includes a sequencer block that connects to a sequence of coding blocks representative of a control flow and establish data communication with the sequence of coding blocks. The sequencer block includes coding circuitry that receives coding data from the sequence of coding blocks coding data, the coding data representative of instruction code to which the coding blocks corresponds, and generates from the received coding data command data that is representative of a sequence of commands that corresponds to a control flow of which the code blocks in data communication with the sequencer block are representative and a communication subsystem that provides the command data to a controlled system that is external to the code blocks.