calling dex.transfer problem

[mostar]

The function

dex.transfer(10, "SBD", "fabian", "foobar")

is not working as documented in the tutorial
piston-lib/docs/tutorials.rst

It fail on parameter order:

assert asset == self.symbol("SBD") or asset == self.symbol("steem")

If you fix to what the code is expecting:

dex.transfer("fabian",10, "SBD", "foobar")

Then it fail on TypeError: 'module' object is not callable