code: private void checkM() throws DatatypeException, IOException {
          if (context.length() == 0) {
              appendToContext(current);
          }
          current = reader.read();
          appendToContext(current);
          skipSpaces();
  
          checkArg('M', "x coordinate");
          skipCommaSpaces();
          checkArg('M', "y coordinate");
  
          boolean expectNumber = skipCommaSpaces2();
          _checkL('M', expectNumber);
      }
docs: Checks an 'M' command.