parameters: (self, key, value, timeout=None)
return_statement: return True
docstring: Works like :meth:`set` but does not overwrite the values of already
          existing keys.
  
          :param key: the key to set
          :param value: the value for the key
          :param timeout: the cache timeout for the key in seconds (if not
                          specified, it uses the default timeout). A timeout of
                          0 indicates that the cache never expires.
          :returns: Same as :meth:`set`, but also ``False`` for already
                    existing keys.
          :rtype: boolean
docstring_summary: Works like :meth:`set` but does not overwrite the values of already
          existing keys.
docstring_tokens: Works like : meth : set but does not overwrite the values of already existing keys .
function: def add(self, key, value, timeout=None):
          """Works like :meth:`set` but does not overwrite the values of already
          existing keys.
  
          :param key: the key to set
          :param value: the value for the key
          :param timeout: the cache timeout for the key in seconds (if not
                          specified, it uses the default timeout). A timeout of
                          0 indicates that the cache never expires.
          :returns: Same as :meth:`set`, but also ``False`` for already
                    existing keys.
          :rtype: boolean
          """
          return True
function_tokens: def add ( self , key , value , timeout = None ) : return True