This block lets you embed a python module in your flowgraph.
Code you put in this module is accessible in other blocks using the ID of this block. Example:
If you put
a = 2 def double(arg): return 2 * arg
in a Python Module Block with the ID 'stuff' you can use code like
stuff.a # evals to 2 stuff.double(3) # evals to 6
to set parameters of other blocks in your flowgraph.