/in/HW8.cpp:15:35: error: expected ',' or '...' before 'other'
  double Interval(void MySpacetime other) 
                                   ^~~~~
/in/HW8.cpp:15:23: error: invalid use of type 'void' in parameter declaration
  double Interval(void MySpacetime other) 
                       ^~~~~~~~~~~
/in/HW8.cpp:20:2: error: expected ';' after class definition
 }
  ^
  ;
/in/HW8.cpp: In member function 'double MySpacetime::Interval(<type error>)':
/in/HW8.cpp:17:28: error: 'other' was not declared in this scope
      double interval = pow(other.x - x, 2) + pow(other.y - y, 2) + pow(other.z - z, 2) - pow(other.ct - ct, 2);
                            ^~~~~
/in/HW8.cpp:17:28: note: suggested alternative: 'stderr'
      double interval = pow(other.x - x, 2) + pow(other.y - y, 2) + pow(other.z - z, 2) - pow(other.ct - ct, 2);
                            ^~~~~
                            stderr
/in/HW8.cpp:15:23: error: unused parameter 'MySpacetime' [-Werror=unused-parameter]
  double Interval(void MySpacetime other) 
                       ^~~~~~~~~~~
/in/HW8.cpp: At global scope:
/in/HW8.cpp:21:1: error: expected declaration before '}' token
 } 
 ^
cc1plus: all warnings being treated as errors