Java 8: Why You NEED Functional Interfaces
BiPredicate: Represents a predicate (boolean-valued function) of two arguments.
BiFunction: Represents a function that accepts two arguments and produces a result.
BiConsumer: Represents an operation that accepts two input arguments and returns no result.
BinaryOperator: A specialization of BiFunction for the same type of operands and result.
UnaryOperator: A specialization of Function for the same type of operand and result.