code: def arcsine_sqrt_transform(rel_abd):
      
      arcsint = lambda p: math.asin(math.sqrt(p))
      return {col_id: {row_id: arcsint(rel_abd[col_id][row_id])
                       for row_id in rel_abd[col_id]} for col_id in rel_abd}
docs: Takes the proportion data from relative_abundance() and applies the
      variance stabilizing arcsine square root transformation:
  
      X = sin^{-1} \sqrt p