CAPTCHA's implementation
[Various accompanying utilities]

Collaboration diagram for CAPTCHA's implementation:

Classes
class	BackgroundDrawer
class	CellBackgroundDrawer
class	CircleBackgroundDrawer
class	CodeGenerator
class	Color
class	ColorArray
class	CurvedStringDrawer
class	Drawer
class	ErrorDrawer
class	InclinedStringDrawer
class	LinearStringDrawer
class	RandomLinesBackgroundDrawer
class	TextDrawer
class	TuringImage
class	WavesBackgroundDrawer

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