/in/foo.c:1:1: error: unknown type name 'def'
 def left(x):
 ^~~
/in/foo.c: In function 'left':
/in/foo.c:1:12: error: expected declaration specifiers before ':' token
 def left(x):
            ^
/in/foo.c:1:5: warning: type of 'x' defaults to 'int' [-Wimplicit-int]
 def left(x):
     ^~~~
/in/foo.c:16:5: warning: control reaches end of non-void function [-Wreturn-type]
     print("yes")
     ^~~~~