code: def _eq(
      seg, focus_freq, bandwidth=100, mode="peak", gain_dB=0, order=2
  ):
      """
      Args:
          focus_freq - middle frequency or known frequency of band (in Hz)
          bandwidth - range of the equalizer band
          mode - Mode of Equalization(Peak/Notch(Bell Curve),High Shelf, Low Shelf)
          order - Rolloff factor(1 - 6dB/Octave 2 - 12dB/Octave)
  
      Returns:
          Equalized/Filtered AudioSegment
      """
      filt_mode = ["peak", "low_shelf", "high_shelf"]
      if mode not in filt_mode:
          raise ValueError("Incorrect Mode Selection")
  
      if gain_dB >= 0:
          if mode == "peak":
              sec = band_pass_filter(
                  seg,
                  focus_freq - bandwidth / 2,
                  focus_freq + bandwidth / 2,
                  order=order,
              )
              seg = seg.overlay(sec - (3 - gain_dB))
              return seg
  
          if mode == "low_shelf":
              sec = low_pass_filter(seg, focus_freq, order=order)
              seg = seg.overlay(sec - (3 - gain_dB))
              return seg
  
          if mode == "high_shelf":
              sec = high_pass_filter(seg, focus_freq, order=order)
              seg = seg.overlay(sec - (3 - gain_dB))
              return seg
  
      if gain_dB < 0:
          if mode == "peak":
              sec = high_pass_filter(
                  seg, focus_freq - bandwidth / 2, order=order
              )
              seg = seg.overlay(sec - (3 + gain_dB)) + gain_dB
              sec = low_pass_filter(
                  seg, focus_freq + bandwidth / 2, order=order
              )
              seg = seg.overlay(sec - (3 + gain_dB)) + gain_dB
              return seg
  
          if mode == "low_shelf":
              sec = high_pass_filter(seg, focus_freq, order=order)
              seg = seg.overlay(sec - (3 + gain_dB)) + gain_dB
              return seg
  
          if mode == "high_shelf":
              sec = low_pass_filter(seg, focus_freq, order=order)
              seg = seg.overlay(sec - (3 + gain_dB)) + gain_dB
              return seg
  
imports: from scipy.signal import butter, sosfilt
  from .utils import register_pydub_effect, stereo_to_ms, ms_to_stereo
label_desc: Use image node_id 5 for calling a global function with example usage: _eq(seg, focus_freq, bandwidth, mode, gain_dB, order) and returns: seg, seg, seg, seg, seg, seg