anchor.diff:  
   == Transforming and traversing collections using workers
   
  -+s_mach.concurrent+ provides the +workers+ method allows specifying the maximum number of concurrent operations.
  ++s_mach.concurrent+ provides the +workers+ method which allows specifying the maximum number of concurrent operations.
   
   .Example 3: Using +s_mach.concurrent+ workers to transform and traverse collections:
   [source,scala,numbered]
  
positive.code: 
  
  == Adding progress reporting, retry and throttle control to collection concurrent operations
  +s_mach.concurrent+ allows modifying collection concurrent operations to report progress, retry failures and limit
  iteration speed to a specific time period.
  
  .Example 4: Adding progress reporting, retry and throttle control to collection concurrent operations
  [source,scala,numbered]
  
negative.code: }
  ----
  
  For concurrent operation, all of the futures must be started before the for-comprehension. The for-comprehension is a
  monadic workflow which captures commands that must take place in a specific sequential order. The pattern in example 2
  is necessary because Scala lacks an applicative workflow which captures commands that may be run in any order.
  +s_mach.concurrent+ adds the method +concurrently+ which is an applicative workflow specifically for futures. This
  method can more concisely express the pattern above:
  
  .Example 7: New +concurrently+ method
  [source,scala,numbered]
  