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`rewind'--reinitialize a file or stream

     #include <stdio.h>
     void rewind(FILE *FP);
`rewind' returns the file position indicator (if any) for the file or
stream identified by FP to the beginning of the file.  It also clears
any error indicator and flushes any pending output.
`rewind' does not return a result.
ANSI C requires `rewind'.
   No supporting OS subroutines are required.