code: public SDVariable step(String name, SDVariable in, double cutoff) {
          validateNumerical("step", in);
          SDVariable ret = f().step(in, cutoff);
          return updateVariableNameAndReference(ret, name);
      }
docs: Elementwise step function:<br>
  out(x) = 1 if x >= cutoff<br>
  out(x) = 0 otherwise<br>
  
  @param name   Name of the output variable
  @param in     Input variable
  @param cutoff Cutoff value for step function
  @return Output variable