Ruby

It would be better to explain this with an example:

> 'a'.length -1 ArgumentError: wrong number of arguments (1 for 0) from (pry):1:in `length' 

Other ways of writing this expression work as expected:

> 'a'.length() -1 => 0 > 'a'.length-1 => 0 > 'a'.length- 1 => 0 > 'a'.length - 1 => 0