Return 'verticalalignment'('va') and 'horizontalalignment'('ha') for given 'pos' (position)

def get_text_alignment(pos):
    """Return 'verticalalignment'('va') and 'horizontalalignment'('ha') for given 'pos' (position)"""
    pos = pos.lower()  # to make it case insensitive
    va, ha = None, None
    if pos == 'nw': va, ha = 'top', 'left'
    elif pos == 'ne': va, ha = 'top', 'right'
    elif pos == 'sw': va, ha = 'bottom', 'left'
    elif pos == 'se': va, ha = 'bottom', 'right'
    else: raise ValueError("Unknown value for 'pos': %s" % (str(pos)))
    return {'va':va, 'ha':ha}