Importing Elixir libraries to Erlang env

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9

I have tested some functions for Elixir in the erlang terminal , and their are failing

(hudson@localhost)5> 'Elixir.String':downcase("hudson").
** exception error: no function clause matching 'Elixir.String':downcase("hudson",default) (lib/string.ex, line 785)
(hudson@localhost)6> 'Elixir.String':downcase("hudson","utf-8").
** exception error: no function clause matching 'Elixir.String':downcase("hudson","utf-8") (lib/string.ex, line 785)
(hudson@localhost)7> 'Elixir.String':downcase("hudson",default).
** exception error: no function clause matching 'Elixir.String':downcase("hudson",default) (lib/string.ex, line 785)