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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 save_file(self, obj):
 """Save a file"""

        try:
            import StringIO as pystringIO #we can't use cStringIO as it lacks the name attribute
        except ImportError:
            import io as pystringIO

        if not hasattr(obj, 'name') or  not hasattr(obj, 'mode'):
            raise pickle.PicklingError("Cannot pickle files that do not map to an actual file")
        if obj is sys.stdout:
            return self.save_reduce(getattr, (sys,'stdout'), obj=obj)
        if obj is sys.stderr:
            return self.save_reduce(getattr, (sys,'stderr'), obj=obj)
        if obj is sys.stdin:
            raise pickle.PicklingError("Cannot pickle standard input")
        if obj.closed:
            raise pickle.PicklingError("Cannot pickle closed files")
        if hasattr(obj, 'isatty') and obj.isatty():
            raise pickle.PicklingError("Cannot pickle files that map to tty objects")
        if 'r' not in obj.mode and '+' not in obj.mode:
            raise pickle.PicklingError("Cannot pickle files that are not opened for reading: %s" % obj.mode)

        name = obj.name

        retval = pystringIO.StringIO()

        try:
            # Read the whole file
            curloc = obj.tell()
            obj.seek(0)
            contents = obj.read()
            obj.seek(curloc)
        except IOError:
            raise pickle.PicklingError("Cannot pickle file %s as it cannot be read" % name)
        retval.write(contents)
        retval.seek(curloc)

        retval.name = name
        self.save(retval)
        self.memoize(obj)