Function group cast

Cast object to a predefine type Function group has those functions and groups:

• Function as_boolean - return the Boolean if the argument is a Boolean, nothing if it's not.
• Function as_number - return the number if the argument is a number, nothing if it's not.
• Function as_string - return the string if the argument is a string, nothing if it's not.
• Function as_array - return the array if the argument is an array, nothing if it's not.
• Function as_object - return the object if the argument is an object, nothing if it's not.

Use additional help with a function name to see more details about the function.