Crate yarns

Functions

concat	Concatenates two strings.
contains	Returns wether a given String contains the given Substring.
head	Gets the first char of a string, and returns it as string.
len	Returns the length of the utf-8 representation of a string.
read	Shortcut for simple binding of user input to an immutable String.
substr	Returns a new string starting at the index provided in the second argument, going the length provided as the third argument.