def map_quads(coord):
    """
    Map a quadrant number to Moran's I designation
    HH=1, LH=2, LL=3, HL=4
    Args:
      coord (int): quadrant of a specific measurement
    Returns:
      classification (one of 'HH', 'LH', 'LL', or 'HL')
    """
    if coord == 1:
        return 'HH'
    elif coord == 2:
        return 'LH'
    elif coord == 3:
        return 'LL'
    elif coord == 4:
        return 'HL'
    return None