docs: def get_bottom(depths, des_mask, asc_mask):
      '''Get boolean mask of regions in depths the animal is at the bottom
  
      Args
      ----
      des_mask: ndarray
          Boolean mask of descents in the depth data
      asc_mask: ndarray
          Boolean mask of ascents in the depth data
  
      Returns
      -------
      BOTTOM: ndarray (n,4)
          Indices and depths for when the animal is at the bottom
  
          *Index positions*:
  
          0. start ind
          1. depth at start
          2. stop ind
          3. depth at stop
      '''
      import numpy
  
      from . import utils
  
      # Get start/stop indices for descents and ascents
      des_start, des_stop = utils.contiguous_regions(des_mask)
      asc_start, asc_stop = utils.contiguous_regions(asc_mask)
  
      # Bottom time is at stop of descent until start of ascent
      bottom_len = min(len(des_stop), len(asc_start))
      bottom_start = des_stop[:bottom_len]
      bottom_stop  = asc_start[:bottom_len]
  
      BOTTOM = numpy.zeros((len(bottom_start),4), dtype=float)
  
      # Time (seconds) at start of bottom phase/end of descent
      BOTTOM[:,0] = bottom_start
  
      # Depth (m) at start of bottom phase/end of descent
      BOTTOM[:,1] = depths[bottom_start]
  
      # Time (seconds) at end of bottom phase/start of asscent
      BOTTOM[:,2] = bottom_stop
  
      # Depth (m) at end of bottom phase/start of descent
      BOTTOM[:,3] = depths[bottom_stop]
  
      return BOTTOM