pool(...)....pool is generic. There are methods for several
  classes, listed below.
  
  pool is used to combine the data from several objects of the same type,
  and to compute statistics based on the combined dataset.
  It is typically used in high-performance computing applications,
  when the objects ... have been computed on different processors
  or in different batch runs, and we wish to combine them.pool.envelope,
  pool.fasp