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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 _track_class_field(cls, field):
 """ Track a field on the current model """

    if '__' in field:
        _track_class_related_field(cls, field)
        return
    # Will raise FieldDoesNotExist if there is an error
    cls._meta.get_field(field)
    # Detect m2m fields changes
    if isinstance(cls._meta.get_field(field), ManyToManyField):
        m2m_changed.connect(
            tracking_m2m,
            sender=getattr(cls, field).through,
            dispatch_uid=repr(cls),
        )