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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 begin_access(self, cursor=None, offset=0, size=sys.maxsize, flags=0):
 """Call this before the first use of this instance. The method was already called by the constructor in case sufficient information was provided. For more information no the parameters, see the __init__ method :param path: if cursor is None the existing one will be used. :return: True if the buffer can be used"""

        if cursor:
            self._c = cursor
        # END update our cursor

        # reuse existing cursors if possible
        if self._c is not None and self._c.is_associated():
            res = self._c.use_region(offset, size, flags).is_valid()
            if res:
                # if given size is too large or default, we computer a proper size
                # If its smaller, we assume the combination between offset and size
                # as chosen by the user is correct and use it !
                # If not, the user is in trouble.
                if size > self._c.file_size():
                    size = self._c.file_size() - offset
                # END handle size
                self._size = size
            # END set size
            return res
        # END use our cursor
        return False