message: Clean up span computation
diff: @@ -56,14 +56,10 @@ impl<'input> Term<&'input str> {
  Term::FunctionType(param_type, body_type) => {
  param_type.span().start..body_type.span().end
  }
  - Term::FunctionElim(head, arguments) => {
  - let head_span = head.span();
  - head_span.start
  - ..arguments
  - .last()
  - .map(|argument| argument.span().end)
  - .unwrap_or(head_span.end)
  - }
  + Term::FunctionElim(head, arguments) => match arguments.last() {
  + Some(argument) => head.span().start..argument.span().end,
  + None => head.span(),
  + },
  }
  }
  }
  