Factory method to create a chain of Flatten+StaticFeatureSelection Mappers
Parameters :
mask : None or array
an array in the original dataspace and its nonzero elements are
used to define the features included in the dataset. Alternatively,
the shape argument can be used to define the array dimensions.
shape : None or tuple
The shape of the array to be mapped. If shape is provided instead
of mask, a full mask (all True) of the desired shape is
constructed. If shape is specified in addition to mask, the
provided mask is extended to have the same number of dimensions.