def p_concrete_integer(self, p):
    ' concrete_integer_expression : INT_CONST_DEC\n                                        | MINUS INT_CONST_DEC '
    if (len(p) == 3):
        p[0] = (- int(p[2]))
    else:
        p[0] = int(p[1])
concrete_integer_expression : INT_CONST_DEC
| MINUS INT_CONST_DEC
def p_concrete_integer(self, p):
    ' concrete_integer_expression : INT_CONST_DEC\n                                        | MINUS INT_CONST_DEC '
    if (len(p) == 3):
        p[0] = (- int(p[2]))
    else:
        p[0] = int(p[1])