I'm not certain I understand how their use of _ is any different from Lo-dash or Underscore's use of the variable. Just because they're not first to the party

I'm not certain I understand how their use of _ is any different from Lo-dash or Underscore's use of the variable. Just because they're not first to the party doesn't mean they can't hop on the established semantics. Their use of _ actually made it easier for me to follow their examples.