code: public static Boolean checkInfrontBehind(MatchResult r, Sentence s) {
  		Boolean ok = true;
  		
  		// get rid of expressions such as "1999" in 53453.1999
  		if (r.start() > 1) {
  			if ((s.getCoveredText().substring(r.start() - 2, r.start()).matches("\\d\\."))){
  				ok = false;
  			}
  		}
  		
  		// get rid of expressions if there is a character or symbol ($+) directly in front of the expression
  		if (r.start() > 0) {
  			if (((s.getCoveredText().substring(r.start() - 1, r.start()).matches("[\\w\\$\\+]"))) &&
  					(!(s.getCoveredText().substring(r.start() - 1, r.start()).matches("\\(")))){
  				ok = false;
  			}
  		}
  		
  		if (r.end() < s.getCoveredText().length()) {
  			if ((s.getCoveredText().substring(r.end(), r.end() + 1).matches("[°\\w]")) &&
  					(!(s.getCoveredText().substring(r.end(), r.end() + 1).matches("\\)")))){
  				ok = false;
  			}
  			if (r.end() + 1 < s.getCoveredText().length()) {
  				if (s.getCoveredText().substring(r.end(), r.end() + 2).matches(
  						"[\\.,]\\d")) {
  					ok = false;
  				}
  			}
  		}
  		return ok;
  	}
docs: Check token boundaries of expressions.
  @param r MatchResult
  @param s Respective sentence
  @return whether or not the MatchResult is a clean one