def get(obj, field):
    """
    Extracts field value from nested object

    :type obj: ``dict``
    :param obj: The object to extract the field from

    :type field: ``str``
    :param field: The field to extract from the object, given in dot notation

    :return: The value of the extracted field
    :rtype: ``str``
    """
    parts = field.split(".")
    for part in parts:
        if obj and part in obj:
            obj = obj[part]
        else:
            return None
    return obj