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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 parse(self, stream, media_type=None, parser_context=None):
 """ Parses the incoming bytestream as YAML and returns the resulting data. """

        assert yaml, 'YAMLParser requires pyyaml to be installed'

        parser_context = parser_context or {}
        encoding = parser_context.get('encoding', settings.DEFAULT_CHARSET)

        try:
            data = stream.read().decode(encoding)
            return yaml.safe_load(data)
        except (ValueError, yaml.parser.ParserError) as exc:
            raise ParseError('YAML parse error - %s' % six.text_type(exc))