MicroPython

MicroPython is a release of Python for use on MCU.

MicroPython is available also for STM32F4xx (STM32F4-DISCOVERY), see here.
See also this tutorial for run MicroPython on NUCLEO-F401RE. In Italian language is here.

MicroPython documentation is here.
MicroPython tutorial is here.

There are some MicroPython boards based on STM32F4 ready to use, see here.