Compiling that code produces many errors. Where did you get it from ?
Arduino: 1.8.5 (Windows 10), Board: "Arduino Nano, ATmega328P"
C:\Users\Bob\AppData\Local\Temp\arduino_modified_sketch_170471\sketch_may12a.ino: In function 'void setup()':
sketch_may12a:14: error: 'set_feedrate' was not declared in this scope
set_feedrate(200); // set default speed
^
C:\Users\Bob\AppData\Local\Temp\arduino_modified_sketch_170471\sketch_may12a.ino: In function 'void help()':
sketch_may12a:24: error: 'VERSION' was not declared in this scope
Serial.println(VERSION);
^
C:\Users\Bob\AppData\Local\Temp\arduino_modified_sketch_170471\sketch_may12a.ino: In function 'void processCommand()':
sketch_may12a:76: error: 'parsenumber' was not declared in this scope
int cmd = parsenumber('G', -1);
^
sketch_may12a:81: error: 'fr' was not declared in this scope
set_feedrate(parsenumber('F', fr));
^
sketch_may12a:81: error: 'set_feedrate' was not declared in this scope
set_feedrate(parsenumber('F', fr));
^
sketch_may12a:82: error: 'mode_abs' was not declared in this scope
line( parsenumber('X', (mode_abs ? px : 0)) + (mode_abs ? 0 : px),
^
sketch_may12a:82: error: 'px' was not declared in this scope
line( parsenumber('X', (mode_abs ? px : 0)) + (mode_abs ? 0 : px),
^
sketch_may12a:83: error: 'py' was not declared in this scope
parsenumber('Y', (mode_abs ? py : 0)) + (mode_abs ? 0 : py) );
^
sketch_may12a:88: error: 'pause' was not declared in this scope
pause(parsenumber('P', 0) * 1000);
^
sketch_may12a:98: error: 'position' was not declared in this scope
parsenumber('Y', 0) );
^
sketch_may12a:108: error: 'm1' was not declared in this scope
m1.release();
^
sketch_may12a:109: error: 'm2' was not declared in this scope
m2.release();
^
sketch_may12a:115: error: 'where' was not declared in this scope
where();
^
C:\Users\Bob\AppData\Local\Temp\arduino_modified_sketch_170471\sketch_may12a.ino: At global scope:
sketch_may12a:122: error: expected constructor, destructor, or type conversion before '(' token
parsenumber(key, default)
^
exit status 1
'set_feedrate' was not declared in this scope
This report would have more information with
"Show verbose output during compilation"
option enabled in File -> Preferences.