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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def registerExitCall():
 r"""Registers an exit call to start the core. The core would be started after the main module is loaded. Ec would be exited from the core. """

  if state.isExitHooked:
    return

  state.isExitHooked = True

  from atexit import register

  register(core.start)