'Checks if a file exists already and if it does whether it\'s bigger or smaller than
the file we are post processing
;param existing_file: The file to compare to
:return:
DOESNT_EXIST if the file doesn\'t exist
EXISTS_LARGER if the file exists and is larger than the file we are post processing
EXISTS_SMALLER if the file exists and is smaller than the file we are post processing
EXISTS_SAME if the file exists and is the same size as the file we are post processing'

def _checkForExistingFile(self, existing_file):

    if (not existing_file):
        self._log(u"There    is    no    existing    file    so    there's    no    worries    about    replacing    it", logger.DEBUG)
        return PostProcessor.DOESNT_EXIST
    if ek(os.path.isfile, existing_file):
        if (ek(os.path.getsize, existing_file) > ek(os.path.getsize, self.file_path)):
            self._log((((u'File    ' + existing_file) + u'    is    larger    than    ') + self.file_path), logger.DEBUG)
            return PostProcessor.EXISTS_LARGER
        elif (ek(os.path.getsize, existing_file) == ek(os.path.getsize, self.file_path)):
            self._log((((u'File    ' + existing_file) + u'    is    the    same    size    as    ') + self.file_path), logger.DEBUG)
            return PostProcessor.EXISTS_SAME
        else:
            self._log((((u'File    ' + existing_file) + u'    is    smaller    than    ') + self.file_path), logger.DEBUG)
            return PostProcessor.EXISTS_SMALLER
    else:
        self._log(((u'File    ' + existing_file) + u"    doesn't    exist    so    there's    no    worries    about    replacing    it"), logger.DEBUG)
        return PostProcessor.DOESNT_EXIST
