def _validate_transition_missing_symbols(self, start_state, paths):
"""Raise an error if the transition input_symbols are missing."""
for input_symbol in self.input_symbols:
if input_symbol not in paths:
raise exceptions.MissingSymbolError(
'state {} is missing transitions for symbol {}'.format(
start_state, input_symbol))
def _read_input_symbol_subset(self):
if not (self.input_symbols < self.tape_symbols):
raise exceptions.MissingSymbolError(
'The set of tape symbols is missing symbols from the input '
'symbol set ({})'.format(self.tape_symbols -
self.input_symbols))