Case : CASE ArgList COLON Terminator Block
         | DEFAULT COLON Terminator Block

def p_Case(p):
    '''
    Case : CASE ArgList COLON Terminator Block
         | DEFAULT COLON Terminator Block
    '''
    if p[1] == 'case':
        p[0] = Case(p[1], p[2], p[4], p[5])
    else:
        p[0] = Case(p[1], None, p[3], p[4])