Function: length

--Usage--
> length(some_collection)

Returns the number of items in a list or the number of characters in a string.

Note: This function is exactly the same as [[fun:number_of_items]].

--Parameters--
! Parameter	Type				Description
| @input@	[[type:list]] or [[type:map]] or [[type:set]] or [[type:string]]
		  				Object to determine the number of items of.
		  				When it is a set, returns the number of cards.
		  				When it is a string, returns the number of characters.

--Examples--
> length(["x", "y", "z"]) == 3
> length("pink") == 4

--See also--
| [[fun:number_of_items]]	Return the number of items in a list.