def _key_lookup_ignorecase(d, key):
    """ Search dict for key, ignoring case

    Args:
      d (dict): dict to search
      key (str): key to search for

    Returns:
      str or None: key in dict `d` matching `key` if found; else None

    """
    key = [k for k in d.keys() if key.lower() == k.lower()]
    if key:
        return key[0]
    else:
        return None