new_contents: #!/usr/bin/env python
  """Apply a cut on a table & copy to a new file.
  
  You can use pytable's expression syntax to apply logical conditions
  like
  
      sqrt(pos_x**2 + pos_y**2) <= 150.0
  
  using numexpr-like syntax to filter events from a table.
  To only grab the events which fullfill that condition, use `my_table.where()`,
  or the related functions `read_where` and `append_where`.
  """
  
  import sys
  import tables as tb
  
  infile = sys.argv[-2]
  outfile = sys.argv[-1]
  
  h5in = tb.open_file(infile, 'r')
  h5out = tb.open_file(outfile, 'a')
  
  tab_in = h5in.root.mva
  tab_desc = tab_in.description
  filt = tb.Filters(complevel=5)
  tab_out = h5out.create_table('/', 'mva', description=tab_desc, filters=filt)
  
  expr = 'sqrt(tf_r_x**2 + tf_r_y**2) <= 150.0'
  
  tab_in.append_where(tab_out, expr)
  tab_in.close()
  tab_out.close()
  
subject: apply cuts directly via pytables