How to read the BEAM bytecode compiled into memory and that is not on the disk?

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Types can be read from the module’s bytecode like the following at compile-time:

defmodule MyModule do
  @type one_type :: atom()
  @opaque another_type :: integer()

  @after_compile {MyModule, :_collect_types}

  def _collect_types(_env, bytecode) do
    {:ok, types} = Code.Typespec.fetch_types(bytecode)

    Enum.map(types, fn {kind, type} ->
      type_ast = Code.Typespec.type_to_quoted(type)

      type_ast
      |> Macro.to_string()
      |> IO.inspect(label: kind)
    end)
  end
end

it prints:

opaque: "another_type() :: integer()"
type: "one_type() :: atom()"
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