
  -spec a_function(Tuples, Type) -> Function
                      when
                          Function :: a_function(),
                          Tuples :: [tuple()],
                          Type :: type().

  Creates a function. a_function(F, T) is equivalent to 
  from_term(F, T) if the result is a function. If no type is
  explicitly specified, [{atom, atom}] is used as the function
  type.
