Flows are synchronous streams of data. They are named Flows as they are
mostly used in Fluids (but this is not a requirement) and lets the fluid
data flow down into the view. Flows always has a value.
A fluid container is a map of dependencies that can be resolved by a FluidFactory.
a simple type-based container is provided with SimpleFluidContainer.
Holds a reference to dependencies in a map and allows fetching them with
their type. As type is the only qualifier it does not support multiple instances
of the same type.