code: def from_pattern(cls, pattern, filetype=None, key='filename', root=None, ignore=[]):
          
          filepattern = FilePattern(key, pattern, root=root)
          if FileInfo.filetype and filetype is None:
              filetype = FileInfo.filetype
          elif filetype is None:
              raise Exception("The filetype argument must be supplied unless "
                              "an appropriate default has been specified as "
                              "FileInfo.filetype")
          return FileInfo(filepattern, key, filetype, ignore=ignore)
docs: Convenience method to directly chain a pattern processed by
          FilePattern into a FileInfo instance.
  
          Note that if a default filetype has been set on FileInfo, the
          filetype argument may be omitted.