docs: def find_magic_file(self, fname, system_only=False, user_only=False):
          '''
          Finds the specified magic file name in the system / user magic file directories.
  
          @fname       - The name of the magic file.
          @system_only - If True, only the system magic file directory will be searched.
          @user_only   - If True, only the user magic file directory will be searched.
  
          If system_only and user_only are not set, the user directory is always searched first.
  
          Returns the path to the file on success; returns None on failure.
          '''
          loc = None
  
          if not system_only:
              fpath = self._user_path(self.BINWALK_MAGIC_DIR, fname)
              if os.path.exists(fpath) and common.file_size(fpath) > 0:
                  loc = fpath
  
          if loc is None and not user_only:
              fpath = self._system_path(self.BINWALK_MAGIC_DIR, fname)
              if os.path.exists(fpath) and common.file_size(fpath) > 0:
                  loc = fpath
  
          return fpath