All an Adapter needs is the ability to convert a string (containin the data, not a filename)
into an implementation of PSR-7's
StreamInterface specific to your framework.
Some adapters may also choose to implement the
which provides methods for converting strings or arrays into framework-specfic
This must return a
Stream object that implements
StreamInterface whose contents are populated
$input. Implementations may alter the contents of
$input to suit their needs.