def METHOD_NAME(
    querystring, key="MessageAttribute", base="", value_namespace="Value."
):
    message_attributes = {}
    index = 1
    while True:
        # Loop through looking for message attributes
        name_key = base + "{0}.{1}.Name".format(key, index)
        name = querystring.get(name_key)
        if not name:
            # Found all attributes
            break
        data_type_key = base + "{0}.{1}.{2}DataType".format(key, index, value_namespace)
        data_type = querystring.get(data_type_key)
        if not data_type:
            raise MessageAttributesInvalid(
                "The message attribute '{0}' must contain non-empty message attribute value.".format(
                    name[0]
                )
            )
        data_type_parts = data_type[0].split(".")
        if data_type_parts[0] not in [
            "String",
            "Binary",
            "Number",
        ]:
            raise MessageAttributesInvalid(
                "The message attribute '{0}' has an invalid message attribute type, the set of supported type prefixes is Binary, Number, and String.".format(
                    name[0]
                )
            )
        type_prefix = "String"
        if data_type_parts[0] == "Binary":
            type_prefix = "Binary"
        value_key = base + "{0}.{1}.{2}{3}Value".format(key, index, value_namespace, type_prefix)
        value = querystring.get(value_key)
        if not value:
            raise MessageAttributesInvalid(
                "The message attribute '{0}' must contain non-empty message attribute value for message attribute type '{1}'.".format(
                    name[0], data_type[0]
                )
            )
        message_attributes[name[0]] = {
            "data_type": data_type[0],
            type_prefix.lower() + "_value": value[0],
        }
        index += 1
    return message_attributes