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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 init_backends():
 """Loads all backends"""


    global _BACKENDS, _ACTIVE_BACKENDS

    try:
        from .cffi_backend import CFFIBackend
    except ImportError:
        pass
    else:
        _BACKENDS.append(CFFIBackend)

    from .ctypes_backend import CTypesBackend
    from .null_backend import NullBackend

    _BACKENDS.append(CTypesBackend)
    _ACTIVE_BACKENDS = _BACKENDS[:]
    # null isn't active by default
    _BACKENDS.append(NullBackend)