52GNU GENERAL PUBLIC LICENSEVersion 2, June 1991Copyright (C) 1989, 1991 Free Software Foundation, Inc.59 Temple Place, Suite 330, Boston, MA 02111-1307 USAEveryone is permitted to copy and distribute verbatimcopies of this license document, but changing it is notallowed.PreambleThe licenses for most software are designed to take awayyour freedom to share and change it. By contrast, theGNU General Public License is intended to guaranteeyour freedom to share and change free software--to makesure the software is free for all its users. This GeneralPublic License applies to most of the Free SoftwareFoundation’s software and to any other program whoseauthors commit to using it. (Some other Free SoftwareFoundation software is covered by the GNU LibraryGeneral Public License instead.) You can apply it to yourprograms, too.When we speak of free software, we are referring tofreedom, not price. 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And you mustshow them these terms so they know their rights.We protect your rights with two steps: (1) copyright thesoftware, and (2) offer you this license which gives youlegal permission to copy, distribute and/or modify thesoftware.Also, for each author's protection and ours, we want tomake certain that everyone understands that there is nowarranty for this free software. If the software is modifiedby someone else and passed on, we want its recipientsto know that what they have is not the original, so thatany problems introduced by others will not reflect on theoriginal authors’ reputations.Finally, any free program is threatened constantly bysoftware patents. 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