BootPos is an S4 class that provides a common interface
to different algorithms that can be used for implementation of a block
bootstrap procedure in the time domain.
After initialization the bootstrapping can be performed by applying
getPositions to the object.
Different block bootstraps are implemented by creating a subclass together
getPositions method that contains the implementation of the
block resampling procedure.
Currently the following implementations are available:
the (expected) block length for the block bootstrap methods
number of available observations to bootstrap from
Lahiri, S. N. (1999). Theoretical Comparisons of Block Bootstrap Methods. The Annals of Statistics, 27(1), 386–404.