code: public void setTurn(char c, int t) {
  		if (turn[t - 3] == 'X')
  			return;
  		else if (turn[t - 3] == '<' && c == '>' || turn[t - 3] == '>'
  				&& c == '<') {
  			turn[t - 3] = 'X';
  		} else if (turn[t - 3] == '<' || turn[t - 3] == '>')
  			return;
  		else
  			turn[t - 3] = c;
  	}
docs: Set the turn column corresponding to 3,4 or 5 helix patterns. If starting
  > or ending < was set and the opposite is being set, the value will be
  converted to X. If a number was set, it will be overwritten by the new
  character.
  
  @param c
  character in the column
  @param t
  turn of the helix {3,4,5}