f(String name, [String mode = "w+", String charset = 'utf-16']) {
print(name);
print(mode);
print(charset);
print("\n");
}
main() {
f('dart');
f('java', 'y+');
f('c', 'windows-1258');
f('python', 'z+', 'utf-8');
}
/*
run:
dart
w+
utf-16
java
y+
utf-16
c
windows-1258
utf-16
python
z+
utf-8
*/