The following text is the original 'COPYRIGHT' file of tkHTML. 

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Most of the source code for the Tk Html widget has been place in the
public domain.  You can do with it whatever you want.  However, some
files have been copied from other sources and contain copyrights.
A copyright notice appears separately at the top of each source file.
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In this sample, HTML documents are quoted in the 'tests' directory of
tkHTML source tree. There were no copyright notice in the directory.