/in/foo.c:1:1: error: unknown type name 'def'
    1 | def is_leap(year):
      | ^~~
/in/foo.c: In function 'is_leap':
/in/foo.c:1:18: error: expected declaration specifiers before ':' token
    1 | def is_leap(year):
      |                  ^
/in/foo.c:1:5: warning: type of 'year' defaults to 'int' [-Wimplicit-int]
    1 | def is_leap(year):
      |     ^~~~~~~
/in/foo.c:18: warning: control reaches end of non-void function [-Wreturn-type]