<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _only_main(func):
 """Call the given `func` only from the main project"""

    @wraps(func)
    def wrapper(self, *args, **kwargs):
        if not self.is_main:
            return getattr(self.main, func.__name__)(*args, **kwargs)
        return func(self, *args, **kwargs)
    return wrapper