code: def declare_internal(self, function):
          
          function._pyscss_needs_namespace = True
          self._auto_register_function(function, function.__name__, 1)
          return function
docs: Like declare(), but the registered function will also receive the
          current namespace as its first argument.  Useful for functions that
          inspect the state of the compilation, like ``variable-exists()``.
          Probably not so useful for anything else.