View Compilation Error

0_0_1623921_7125.cpp: In member function `bool node::isok()':
0_0_1623921_7125.cpp:16: error: `e' undeclared (first use this function)
0_0_1623921_7125.cpp:16: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_1623921_7125.cpp: At global scope:
0_0_1623921_7125.cpp:18: error: `node e' used prior to declaration