Scala quiz. Can methods, taking one argument, be used with inf

Can methods, taking one argument, be used with infix syntax?

Explanation

Get an explanation when it's available:

Arity-1
Scala has a special syntax for invoking methods of arity-1 (one argument):
```
names.mkString(",")
// is the same as
names mkString ","
```
This syntax is formally known as “infix notation”. It should only be used for purely-functional methods (methods with no side-effects) - such as mkString -or methods which take functions as parameters - such as foreach:
```
// right!
names foreach (n => println(n))
names mkString ","
optStr getOrElse ""
// wrong!
javaList add item
```
Read more: Scala documentation: Method Invocation