<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def contains_plural_field(model, fields):
 """ Returns a boolean indicating if ``fields`` contains a relationship to multiple items. """

    source_model = model
    for orm_path in fields:
        model = source_model
        bits = orm_path.lstrip('+-').split('__')
        for bit in bits[:-1]:
            field = model._meta.get_field(bit)
            if field.many_to_many or field.one_to_many:
                return True
            model = get_model_at_related_field(model, bit)
    return False