Use less λs so as to make debugging easier.

fixes #20
One has to find a balance between debugging comfort and code readability:
Moving 2 single liners into functions of its own appears to me like cluttering the code of the class and thus making it less easy to follow. Moreover the function `transfer_task` should be fair enough as debugging context, so the anonymous lambda name should not matter as much as in the other examples.
What do you think?