old_contents: from .filt import filter
  from .laggedcoherence import lagged_coherence
  from .timefrequency import phase_by_time, amp_by_time, freq_by_time
  from . import shape
  from . import spectral
  
new_contents: from .filt import filter
  from .pac import compute_pac, compute_pac_comodulogram, plot_pac_comodulogram
  from .laggedcoherence import lagged_coherence
  from .timefrequency import phase_by_time, amp_by_time, freq_by_time
  from . import shape
  from . import spectral
  
subject: add pac to init file