'<input>', and for symbol is
'single'. One several things can happen:
None. runsource() returns
The return value can be used to decide whether to use
sys.ps2 to prompt the next line.
A note about KeyboardInterrupt: this exception may occur elsewhere in this code, and may not always be caught. The caller should be prepared to deal with it.
'<string>'when reading from a string. The output is written by the write() method.
sys.stderr). Derived classes should override this to provide the appropriate output handling as needed.