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+% This macro source file is from the four volume series
+% "TeX in Practice" by Stephan von Bechtolsheim, published
+% 1993 by Springer-Verlag, New York.
+% Copyright 1993 Stephan von Bechtolsheim.
+% No warranty or liability is assumed.
+% This macro may be copied freely if no fees other than
+% media cost or shipping charges are charged and as long
+% as this copyright and the following source code itself
+% is not changed. Please see the series for further information.
+%
+% Version: 1.0
+% Date: May 1, 1993
+%
+%
+% This source code is documented in 23.4.8.1, p. III-266.
+% Original source in file "macros3.TEX", starting line 1514.
+\wlog{L: "defauarg.tip" ["macros3.TEX," l. 1514, p. III-266]}%
+% This file DOES belong to format "texip."
+\InputD{gobblemo.tip}
+\catcode`\@ = 11
+\def\DefaultArg #1#2#3{%
+ \def\@DefaultArgMacro{#1}%
+ \edef\@EmptyOtherArg{#2}%
+ \edef\@DefaultArgDefault{#3}%
+ \@DefaultArg #2\@DefaultArgEnd
+}
+\def\@DefaultArg{%
+ \futurelet\@DefaultArgSymbol\@DefaultArgOne
+}
+\def\@DefaultArgOne{%
+ \ifx\@DefaultArgSymbol\@DefaultArgEnd
+ \expandafter\edef\@DefaultArgMacro{\@DefaultArgDefault}%
+ \else
+ \expandafter\edef\@DefaultArgMacro{\@EmptyOtherArg}%
+ \fi
+ \GobbleDoMore{\@DefaultArgEnd}{\relax}%
+}
+\catcode`\@ = 12