def peek(self, n=1):
        if n > len(self._readbuffer) - self._offset:
            chunk = self.read(n)
            self._offset -= len(chunk)

        # Return up to 512 bytes to reduce allocation overhead for tight loops.
        return self._readbuffer[self._offset: self._offset + 512]
convert a json string and return a SchemaDocument
dataset/ETHPy150Open AndroBugs/AndroBugs_Framework/tools/modified/androguard/patch/zipfile.py/ZipExtFile.peek--crossover with--dataset/ETHPy150Open namlook/mongokit/mongokit/document.py/Document.from_json