@spec add_alias(
  Igniter.t(),
  atom() | String.t(),
  String.t() | {:code, term()} | [String.t() | {:code, term()}],
  opts :: Keyword.t()
) :: Igniter.t()

Adds an alias to the mix.exs file

Options

• :if_exists - How to alter the alias if it already exists. Options are:
• :ignore - Do nothing if the alias already exists. This is the default.
• :prepend - Add the new alias to the beginning of the list (if it is not already present).
• {:prepend, value} - Add a different value than the originally supplied alias to the beginning of the list (if it is not already present).
• {:replace_or_append, old, new} - If the old value is in the list, it is replaced with the new value. Otherwise the new value is appended (if it is not already present).
• :append - Add the new alias to the end of the list (if it is not already present).
• {:append, value} - Add a different value than the originally supplied alias to the end of the list (if it is not already present).
• :warn - Print a warning if the alias already exists.

@spec modify_existing_alias(
  Igniter.t(),
  atom() | String.t(),
  (Sourceror.Zipper.t() -> {:ok, Sourceror.Zipper.t()} | :error)
) :: Igniter.t()

Modifies an existing alias, doing nothing if it doesn't exist