docs: def pivot(self, attrlist):
          """Pivots the data using the given attributes, returning a L{PivotTable}.
              @param attrlist: list of attributes to be used to construct the pivot table
              @type attrlist: list of strings, or string of space-delimited attribute names
          """
          if isinstance(attrlist, basestring):
              attrlist = attrlist.split()
          if all(a in self._indexes for a in attrlist):
              return PivotTable(self, [], attrlist)
          else:
              raise ValueError("pivot can only be called using indexed attributes")