FlexiFlow is a widget that provides a design size to its child and
enables the possibility to use the size extensions.
designSize is the size that you designed your app for, like 375x812.
You can take this size from your design tool.
FlowScreen is a widget that will build a different widget
depending on the device size.
He has three parameters, mobileChild, tabletChild and desktopChild
and depending on the device size, one of them will be built.
If you need a different parameter for responsive, you can use the
FlowBuilder widget, creating your own flow with the IFlow interface.
Interface class for create custom flows.
Type is the type of the flow, you can use
a enum, object or any type that you need.
getCurrentType is the current type of the flow. It's used to return the
current type based on some logic, like the screen size.
getCurrentFlow is the current flow based on the current type. It's used to
return the current flow widget based on the current type.
