Cyclesim.Privatetype port_list = Port_list.tval create : 
  ?circuit:Circuit.t ->
  in_ports:port_list ->
  out_ports_before_clock_edge:port_list ->
  out_ports_after_clock_edge:port_list ->
  internal_ports:port_list ->
  reset:task ->
  cycle_check:task ->
  cycle_before_clock_edge:task ->
  cycle_at_clock_edge:task ->
  cycle_after_clock_edge:task ->
  lookup_reg:( Base.string -> Bits.Mutable.t Base.option ) ->
  lookup_mem:( Base.string -> Bits.Mutable.t Base.array Base.option ) ->
  assertions:Bits.Mutable.t Base.Map.M(Base.String).t ->
  Base.unit ->
  t_port_listmodule Step : sig ... end