pip install pytest-monkeytype

# Generate annotations by running your pytest tests as usual:
py.test --monkeytype-output=./monkeytype.sqlite3

# Get a listing of modules annotated by monkeytype
monkeytype list-modules

# Generate a stub file for those annotations using monkeytype:
monkeytype stub some.module

# Apply these annotations directly
monkeytype apply some.module