docs: def create(cls, **kw):
          """
          Create an instance of this class, first cleaning up the keyword
          arguments so they will fill in any required values.
  
          @return: an instance of C{cls}
          """
          for k, v in kw.items():
              attr = getattr(cls, k, None)
              if isinstance(attr, RecordAttribute):
                  kw.pop(k)
                  kw.update(attr._decompose(v))
          return cls(**kw)