OkThen.Result.is_error

You're seeing just the macro is_error, go back to OkThen.Result module for more information.
Link to this macro

is_error(value)

(macro)

Returns true if result is tagged :error.

Equivalent to is_tagged(value, :error). See is_tagged/2.

Examples

iex> Result.is_error(:error)
true

iex> Result.is_error({:error, "hello"})
true

iex> Result.is_error({:ok, "hello"})
false