Create convenience methods to allow or deny all

lib/basic_signup_allowlist.ex

@@ -13,6 +13,7 @@ defmodule BasicSignupAllowlist do
   @spec signup_allowlist_emails() :: String.t()
   def signup_allowlist_emails, do: @signup_allowlist_emails
 
+
   @doc """
   Checks if an email address is allowed based on the SIGNUP_ALLOWLIST_EMAILS env variable.
 
@@ -26,10 +27,10 @@ defmodule BasicSignupAllowlist do
 
   ## Examples
 
-      iex> System.delete_env("SIGNUP_ALLOWLIST_EMAILS")
+      iex> BasicSignupAllowlist.forbid_signup_with_any_email() 
       iex> BasicSignupAllowlist.signup_allowed?("joe@example.com")
       false
-      iex> System.put_env("SIGNUP_ALLOWLIST_EMAILS", "*")
+      iex> BasicSignupAllowlist.allow_signup_with_all_emails() 
       iex> BasicSignupAllowlist.signup_allowed?("joe@example.com")
       true
 
@@ -39,4 +40,12 @@ defmodule BasicSignupAllowlist do
     env_value = System.get_env(@signup_allowlist_emails)
     signup_allowed_fun(env_value, email)
   end
+
+  def allow_signup_with_all_emails() do
+      System.put_env(signup_allowlist_emails(), "*")
+  end
+  
+  def forbid_signup_with_any_email() do
+      System.delete_env(signup_allowlist_emails())
+  end
 end