Free function

In the Swift 2 guide there is this line :
p. 133: find() is no longer available as a free function. It is now CollectionType.indexOf(_:):

Could you please explain what is a “free function” ?

Thanks

A free function is one that does not require an object instance to invoke it on. For example, the print function in Swift is a free function.

print ("Jibber Jabber")       // free

foo.print ("Jibber Jabber")   // not free - bound to foo

Thanks