.ifpresent value:{Dynamic} mapping:{Lambda} -> Any
Maps value to the result of mapping.
.isnone value:{Dynamic} -> Boolean
Checks whether value represents a none value.
.none -> None
.otherwise value:{Dynamic} fallback:{Dynamic} -> Dynamic
Returns value if it is not none, fallback otherwise.
.takeif value:{Dynamic} condition:{Lambda} -> Any
Keeps value if condition is true, otherwise returns none.