'<input>', and for
symbol is 'single'. One several things can happen:
0.
None.
runsource() returns 1.
0.
The return value can be used to decide whether to use
sys.ps1 or 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.