old_contents: """Mock module for Sphinx autodoc."""
  
  
  class FFI(object):
  
      def cdef(self, _):
          pass
  
      def dlopen(self, _):
          return self
  
      SFC_GET_FORMAT_INFO = NotImplemented
  
new_contents: """Mock module for Sphinx autodoc."""
  
  
  class FFI(object):
  
      def cdef(self, _):
          pass
  
      def dlopen(self, _):
          return self
  
      def string(self, _):
          return b'not implemented'
  
      def sf_version_string(self):
          return NotImplemented
  
      SFC_GET_FORMAT_INFO = NotImplemented
  
subject: Add missing member functions in fake CFFI class