[oe] bitbake type and scope of methods question

[David Farning]

I am working defining the various types of methods one can use when
creating bitbake classes and recipies.

1 bitbake-standard method

method_name(){
  ...
  shell script
  ...
}

arguments: None
scope: available in current file or if inherited
called: method_name


2 bitbake-python method

python method_name(){
  ...
  python script
  ...
}

arguments: none
scope: available in current file or if inherited
called: method_name


3 python method

def method_name(args):
  ...
  python script
  ...

arguments: normal python
scope: available in current file or if inherited
called:  ${@method_name(args)}


What is the purpose of EXPORT_FUNCTIONS?
Is there a notion of scope?  Can bbclasses have private methods?

Thanks
David Farning