code: public String letterify(String letterString, char from, char to) {
  		return replaceSymbolWithCharsFromTo(letterString, '?', from, to);
  	}
docs: Replaces all {@code '?'} characters with random chars from [{@code from} - {@code to}] range
  
  @param letterString text to process
  @param from         start of the range
  @param to           end of the range
  @return text with replaced {@code '?'} chars