This is the gr-scigen package. It contains signal processing blocks to
perform FFTs and FFT-related functionality.

The Python namespace is in gnuradio.scigen, which would be normally
imported as:

    from gnuradio import scigen

See the Doxygen documentation for details about the blocks available
in this package. A quick listing of the details can be found in Python
after importing by using:

    help(scigen)