def add_comments_to_configuration_sequence(config, schema, indent=0):
    """
    If the given config sequence's items are maps, then mine the schema for the description of the
    map's first item, and slap that atop the sequence. Indent the comment the given number of
    characters.

    Doing this for sequences of maps results in nice comments that look like:

    ```
    things:
          # First key description. Added by this function.
        - key: foo
          # Second key description. Added by add_comments_to_configuration_map().
          other: bar
    ```
    """
    if 'map' not in schema['seq'][0]:
        return
    for field_name in config[0].keys():
        field_schema = schema['seq'][0]['map'].get(field_name, {})
        description = field_schema.get('desc')
        if not field_schema or not description:
            return
        config[0].yaml_set_start_comment(description, indent=indent)
        return
