code: def search(cls, name, lookup=[]):
          
          if os.path.isfile(name): return name
          for spath in lookup:
              fname = os.path.join(spath, name)
              if os.path.isfile(fname):
                  return fname
              for ext in cls.extensions:
                  if os.path.isfile('%s.%s' % (fname, ext)):
                      return '%s.%s' % (fname, ext)
docs: Search name in all directories specified in lookup.
          First without, then with common extensions. Return first hit.