new_contents: import numpy
  import rasterio
  import os
  #import subprocess
  
  #Set to path of your rasterio folder
  os.chdir(u'D:\\rasterio\\')
  with rasterio.drivers():
  
      # Read raster bands directly to Numpy arrays.
      with rasterio.open('rasterio/tests/data/RGB.byte.tif') as src:
          r, g, b = map(src.read_band, (1, 2, 3))
  
      # Combine arrays using the 'iadd' ufunc. Expecting that the sum will
      # exceed the 8-bit integer range, initialize it as 16-bit. Adding other
      # arrays to it in-place converts those arrays up and preserves the type
      # of the total array.
      total = numpy.zeros(r.shape, dtype=rasterio.uint16)
      for band in (r, g, b):
          total += band
      total /= 3
      assert total.dtype == rasterio.uint16
  
      # Write the product as a raster band to a new 8-bit file. For keyword
      # arguments, we start with the meta attributes of the source file, but
      # then change the band count to 1, set the dtype to uint8, and specify
      # LZW compression.
      kwargs = src.meta
      kwargs.update(
          dtype=rasterio.uint8,
          count=1,
          compress='lzw')
  
      with rasterio.open('example-total.tif', 'w', **kwargs) as dst:
          dst.write_band(1, total.astype(rasterio.uint8))
  
  # Dump out gdalinfo's report card and open the image.
  ##info = subprocess.check_output(
  ##    ['gdalinfo', '-stats', 'example-total.tif'])
  ##print(info)
  ##subprocess.call(['open', 'example-total.tif'])
  os.startfile('example-total.tif')
  
subject: Create total.py