Comment 0 for bug 603953

Currently all variables have to be defined by a data statement, before they can be used.
This leads to clumsy code.

Therefore implement assignment without defining the variable first (no data statement.)

- Maybe limit feature to body of functions.

- However if type inference and role inference finally works there should be no problem
  to allow it everywhere.
  - Inferring the role of "a + b", for which an intermediate variable has to be possibly created
    is the same as inferring the role of "c" in "c = a + b".

- Putting function arguments into the function's namespace could be handled this way too.
  A unified mechanism would simplify the interpreter.