code: def ensure_standard_filter_columns(self, low_frequency_cutoff=None):
          
  
          # Make sure we have a template duration field
          if not hasattr(self.table, 'template_duration'):
              self.table = self.table.add_fields(np.zeros(len(self.table),
                                       dtype=np.float32), 'template_duration')
  
          # Make sure we have a f_lower field
          if low_frequency_cutoff is not None:
              if not hasattr(self.table, 'f_lower'):
                  vec = np.zeros(len(self.table), dtype=np.float32)
                  self.table = self.table.add_fields(vec, 'f_lower')
              self.table['f_lower'][:] = low_frequency_cutoff
  
          self.min_f_lower = min(self.table['f_lower'])
          if self.f_lower is None and self.min_f_lower == 0.:
              raise ValueError('Invalid low-frequency cutoff settings')
docs: Initialize FilterBank common fields
  
          Parameters
          ----------
          low_frequency_cutoff: {float, None}, Optional
              A low frequency cutoff which overrides any given within the
              template bank file.