Modularization extension for app inventor

is there a tool or extension for make modularization like python?.

You can keep downloaded blocks images of procedures, that you can drag into the Blocks Editor of new projects.

my question ita about to call other aia files like python. or for create function and classes need to build all them in only one file aia. its not possible build many functions?. i think only works using extension for call the function or class or am i wrong?