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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 has_bom(self, filestream):
 """Check if has BOM."""


        content = filestream.read(4)
        if content == b'PK\x03\x04':
            # Zip file found.
            # Return `BINARY_ENCODE` as content is binary type,
            # but don't return None which means we don't know what we have.
            return filters.BINARY_ENCODE
        # We only handle zip files, so if we are checking this, we've already failed.
        return None