Helper to create a new decomposition function

Helper to create a new decomposition function

new_decomposition_definition(.class, .data, ..., .env = caller_env(n =
  2))

Arguments

.class	A decomposition class (typically created with new_decomposition_class()).
.data	A tsibble.
...	The user inputs, such as the formula and any control parameters.
.env	The environment from which the user's objects can be found.