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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 write_iso19115_metadata(layer_uri, keywords, version_35=False):
 """Create metadata object from a layer path and keywords dictionary. This function will save these keywords to the file system or the database. :param version_35: If we write keywords version 3.5. Default to False. :type version_35: bool :param layer_uri: Uri to layer. :type layer_uri: basestring :param keywords: Dictionary of keywords. :type keywords: dict """

    active_metadata_classes = METADATA_CLASSES
    if version_35:
        active_metadata_classes = METADATA_CLASSES35

    if 'layer_purpose' in keywords:
        if keywords['layer_purpose'] in active_metadata_classes:
            metadata = active_metadata_classes[
                keywords['layer_purpose']](layer_uri)
        else:
            LOGGER.info(
                'The layer purpose is not supported explicitly. It will use '
                'generic metadata. The layer purpose is %s' %
                keywords['layer_purpose'])
            if version_35:
                metadata = GenericLayerMetadata35(layer_uri)
            else:
                metadata = GenericLayerMetadata(layer_uri)
    else:
        if version_35:
            metadata = GenericLayerMetadata35(layer_uri)
        else:
            metadata = GenericLayerMetadata(layer_uri)

    metadata.update_from_dict(keywords)
    # Always set keyword_version to the latest one.
    if not version_35:
        metadata.update_from_dict({'keyword_version': inasafe_keyword_version})

    if metadata.layer_is_file_based:
        xml_file_path = os.path.splitext(layer_uri)[0] + '.xml'
        metadata.write_to_file(xml_file_path)
    else:
        metadata.write_to_db()

    return metadata