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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 get_fields(cls):
 """ Returns a dictionary of fields and field instances for this schema. """

        fields = {}
        for field_name in dir(cls):
            if isinstance(getattr(cls, field_name), Field):
                field = getattr(cls, field_name)
                field_name = field.field_name or field_name
                fields[field_name] = field
        return fields