Ruby 2.4 warnings about parentheses after method name

[neontapir]

When running a Ruby program that includes the optimist gem, 3 warnings are shown.

warning: parentheses after method name is interpreted as an argument list, not a decomposed argument

These warnings apply to the optimist gem itself. There are three methods with a space between the method name and the opening parenthesis. Under Ruby 2.4, this causes a warning.