Problem in importing Python module

I have a problem, I use Python 3.6.7 I am making a Flask application with the following structure:

   / app
/ arquivospy

other py files

/ static
/ templates

In the folder / archivospy have a few scripts that I use to read a TXT and register in the DB to generate some means to make some accounts and save to BD has BD query scripts, it has the file that I use in the shell itself, a boy that I inform the name of the file TXT and he automates everything, that is to say inside the folder / archivospy everything working well.

The problem is with which makes the Flask routes, it matters:

import filespy.interfaceBD and this error:

File "", line 7, in
import filespy.interfaceBD
File "/home/karont/SiteHtml/app/arquivospy/", line 2, in
import of the markets
ModuleNotFoundError: In the module named & # 39; defineMarkets & # 39;