View Compilation Error

0_0_25280967_27341.cpp:13:32: error: 'node node::operator*(node, node)' must take either zero or one argument
  node operator *(node a, node b)
                                ^
0_0_25280967_27341.cpp: In function 'll pow_mod(int, int, ll*)':
0_0_25280967_27341.cpp:54:14: error: no match for 'operator*' (operand types are 'node' and 'node')
    ans = ans * a;
              ^
0_0_25280967_27341.cpp:55:9: error: no match for 'operator*' (operand types are 'node' and 'node')
   a = a * a;
         ^