IEx.Helpers.h

You're seeing just the macro h, go back to IEx.Helpers module for more information.

h(term)

Prints the documentation for the given module or for the given function/arity pair.

iex> h(Enum)

It also accepts functions in the format function/arity and module.function/arity, for example:

iex> h(receive/1)
iex> h(Enum.all?/2)
iex> h(Enum.all?)