code: def _expand_pattern(self, pattern):
          
          (globpattern, regexp, fields, types) = self._decompose_pattern(pattern)
          filelist = glob.glob(globpattern)
          expansion = []
  
          for fname in filelist:
              if fields == []:
                  expansion.append((fname, {}))
                  continue
              match = re.match(regexp, fname)
              if match is None: continue
              match_items = match.groupdict().items()
              tags = dict((k,types.get(k, str)(v)) for (k,v) in match_items)
              expansion.append((fname, tags))
  
          return expansion
docs: From the pattern decomposition, finds the absolute paths
          matching the pattern.