code: def emg_features(threshold=0):
      """Return a dictionary of popular features used for EMG time series classification."""
      return {
          "mean_abs_value": mean_abs,
          "zero_crossings": zero_crossing(threshold),
          "slope_sign_changes": slope_sign_changes(threshold),
          "waveform_length": waveform_length,
          "integrated_emg": abs_sum,
          "emg_var": emg_var,
          "simple square integral": abs_energy,
          "root_mean_square": root_mean_square,
          "willison_amplitude": willison_amplitude(threshold),
      }
  
imports: import numpy
  from scipy import stats
label_desc: Use image node_id 4 for calling a global function with example usage: emg_features(threshold) and returns: dict