docs: def select(self, selector):
          '''Transforms each element of a sequence into a new form.
  
          Each element is transformed through a selector function to produce a
          value for each value in the source sequence. The generated sequence is
          lazily evaluated.
  
          Args:
              selector: A unary function mapping a value in the source sequence
                  to the corresponding value in the generated generated sequence.
                  The argument of the selector function (which can have any name)
                  is,
  
                  Args:
                      element: The value of the element
  
                  Returns:
                      The selected value derived from the element value
  
          Returns:
              A generated sequence whose elements are the result of invoking the
              selector function on each element of the source sequence.
          '''
          return self.create(self._pool.imap(selector, iter(self), self._chunksize))