code: def map(self, func, iterable, callback=None):
          
          return self._call_callback(callback, map(func, iterable))
docs: A wrapper around the built-in ``map()`` function to provide a
          consistent interface with the other ``Pool`` classes.
  
          Parameters
          ----------
          worker : callable
              A function or callable object that is executed on each element of
              the specified ``tasks`` iterable. This object must be picklable
              (i.e. it can't be a function scoped within a function or a
              ``lambda`` function). This should accept a single positional
              argument and return a single object.
          tasks : iterable
              A list or iterable of tasks. Each task can be itself an iterable
              (e.g., tuple) of values or data to pass in to the worker function.
          callback : callable, optional
              An optional callback function (or callable) that is called with the
              result from each worker run and is executed on the master process.
              This is useful for, e.g., saving results to a file, since the
              callback is only called on the master thread.
  
          Returns
          -------
          results : generator