Map.fetch-exclamation-mark

You're seeing just the function fetch-exclamation-mark, go back to Map module for more information.

fetch!(map, key)

fetch!(map(), key()) :: value()

Fetches the value for a specific key in the given map, erroring out if map doesn't contain key.

If map contains key, the corresponding value is returned. If map doesn't contain key, a KeyError exception is raised.

Inlined by the compiler.

iex> Map.fetch!(%{a: 1}, :a)
1