How to use [strings.join]

The reference page of strings.join has its arguments, constraints and declaration.

Similar to [strings.concat], except it also takes an optional separating character, allowing you to concatenate a bunch of strings, and making sure each original string is separated by some sequence of strings.

.src
   .:foo
   .:bar
strings.join:x:@.src/*
   .:,

/*
 * Results in "foo,bar"
 */