Raises UndefinedFunctionError for Macro.pipe_warning/1 in 1.6

[Jeff Sandberg]

When attempting to use this library, error messages are raised whenever any "enhanced" pipes are called:

** (UndefinedFunctionError) function Macro.pipe_warning/1 is undefined or private. Did you mean one of:

      * pipe/3

    (elixir) Macro.pipe_warning({{:., [line: 2], [{:__aliases__, [line: 2], [:Enum]}, :at]}, [line: 2], [[1, 2, 3]]})
    (pipe_to) lib/pipe_to.ex:31: anonymous fn/3 in PipeTo."MACRO-~>"/3
    (stdlib) lists.erl:1263: :lists.foldl/3
    (pipe_to) expanding macro: PipeTo.~>/2
    iex:2: (file)

Looking through the elixir source code, it appears that the pipe_warning/1 function was deleted in this commit, in Aug 21 of last year.

[Tai An Su]

Thanks for the report, will fix it these couple days. ❤️