code: @Override
      public void setTessVariable(String key, String value) {
          prop.setProperty(key, value);
      }
docs: Set the value of Tesseract's internal parameter.
  
  @param key variable name, e.g., <code>tessedit_create_hocr</code>,
  <code>tessedit_char_whitelist</code>, etc.
  @param value value for corresponding variable, e.g., "1", "0",
  "0123456789", etc.