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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def do_cat(self, line):
 Concatenates files and sends to stdout. """

        # note: when we get around to supporting cat from stdin, we'll need
        #       to write stdin to a temp file, and then copy the file
        #       since we need to know the filesize when copying to the pyboard.
        args = self.line_to_args(line)
        for filename in args:
            filename = resolve_path(filename)
            mode = auto(get_mode, filename)
            if not mode_exists(mode):
                print_err("Cannot access '%s': No such file" % filename)
                continue
            if not mode_isfile(mode):
                print_err("'%s': is not a file" % filename)
                continue
            cat(filename, self.stdout)