Issue about imp.get_magic()

[laike9m]

Hi rocky, I noticed imp.get_magic() is invokded in 4 places in the codebase, each given a different name. Since imp is deprecated, I would like to replace it with importlib.util.MAGIC_NUMBER, meanwhile put them into one single place. Is there any file that you suggest me to put the magic number into, or you prefer to keep it in multiple places?

[rocky]

First and foremost, thanks for offering help to clean up this mess.

The file xdis.magic is the most low-level of the 4 places and I think the right place to put an imp.get_magic() replacement. In fact all of the files other than magic.py itself import magic.

But some caution needs to be done in using import.lib.util.MAGIC_NUMBER: in the master branch, xdis has to support Python 2.7 to 3.8. and according to the import importlib.util doc importlib.util.MAGIC_NUMBER was added in Python 3.4.

One way to get around this is code like:

def get_magic(): 
   If PYTHON_VERSION >= 3.4: 
       import import.util as import_util
       return import_util.MAGIC_NUMBER
   else:
       import imp
       return imp.get_magic()

[laike9m]

yep, will create a pr