4 examples of 'how to loop back to the beginning of a program python' in Python

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def handle_program(self, prog):
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    super().handle_program(prog)
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    prog.unparsed = '\n'.join(b.unparsed for b in prog.blocks)

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def program():
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    global current_mode
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    emulator.enter_program_mode()
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    current_mode = PROGRAM_MODE
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    current_dir.force_update()

8
def main():
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    p = c.make_program()
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    p.constant('emitselector', cap.OutFile.selector)
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    p.label('hello')
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    p.cstring('Gdkkn,vnqkc \t')
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    p.define('c emit', '0 c-push emitselector invoke ;0')
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    p.define('n add1', '1 + ;1')
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    p.define('p writing',
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             'p b@', c.If('( ( p b@ add1) emit)  p 1 + writing;',
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                          ';0'))
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    p.define('main',
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             '( hello writing)  0 syscall')
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    p.enter()

240
def program(self):
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    '''the begining of a grammar, to implement'''
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    pass