code: @SuppressWarnings("squid:S1067")
      protected boolean isAtStartOfNumber() {
          return input.current().isDigit()
                 || input.current().is('-') && input.next().isDigit()
                 || input.current().is('-') && input.next().is('.') && input.next(2).isDigit()
                 || input.current().is('.') && input.next().isDigit();
      }
docs: Determines if the underlying input is looking at the start of a number.
  <p>
  By default this is either indicated by a digit or by '-' followed by a digit or a '.' followed by a digit.
  
  @return <tt>true</tt> if the current input is the start of a numeric constant, <tt>false</tt> otherwise