code: def _static_identity(cls,
                           domain,
                           dtype,
                           missing_value,
                           window_safe,
                           ndim,
                           params):
          
          return (cls, domain, dtype, missing_value, window_safe, ndim, params)
docs: Return the identity of the Term that would be constructed from the
          given arguments.
  
          Identities that compare equal will cause us to return a cached instance
          rather than constructing a new one.  We do this primarily because it
          makes dependency resolution easier.
  
          This is a classmethod so that it can be called from Term.__new__ to
          determine whether to produce a new instance.