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This file is part of Logtalk <https://logtalk.org/>  
Copyright 1998-2019 Paulo Moura <pmoura@logtalk.org>

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
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    http://www.apache.org/licenses/LICENSE-2.0

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Design pattern:
	Factory Method

Description:
	"Define an interface for creating an object, but let subclasses
	decide which class to instantiate. Factory Method lets a class
	defer instantiation to subclasses."

This pattern can be used with both classes and prototypes.

The sample implementation uses prototypes for simplicity with categories
playing a similar role to abstract classes.
