my $mce = MCE->new(
      max_workers => 8,                   
      chunk_size => 2000,                 
      tmp_dir => $tmp_dir,                
      freeze => \&encode_sereal,          
      thaw   => \&decode_sereal,          
      gather => \@a,                      
      init_relay => 0,                    
      input_data => $input_file,          
      RS         => "\n>",                
      use_slurpio => 1,                   
      parallel_io => 1,                   
      use_threads => 1,                   
      spawn_delay  => 0.035,              
      submit_delay => 0.002,              
      job_delay    => 0.150,              
      on_post_exit => \&on_post_exit,     
      on_post_run => \&on_post_run,       
      user_args => { env => 'test' },     
      user_begin => \&user_begin,         
      user_func => \&user_func,           
      user_end => \&user_end,             
      user_error => \&user_error,         
      user_output => \&user_output,       
      stderr_file => 'err_file',          
      stdout_file => 'out_file',          
      flush_file   => 1,                  
      flush_stderr => 1,                  
      flush_stdout => 1,                  
      interval => {   delay => 0.007 [, max_nodes => 4, node_id => 1 ] },
      sequence => { begin => -1, end => 1 [, step => 0.1 [, format => "%4.1f" ] ] },
      bounds_only => 1,                 
      task_end => \&task_end,           
      task_name => 'string',            
      user_tasks => [ { ... }, { ... }, { ... },],
   );