code: private void processArgument() {
          final StringBuilder argumentBuilder = new StringBuilder();
          while (templateReader.hasNextCharacter()) {
              final char argumentCharacter = templateReader.nextCharacter();
              if (argumentCharacter == syntax.getArgumentClosing()) {
                  final String argument = argumentBuilder.toString().trim(); // Getting actual argument name.
                  if (Strings.startsWith(argument, syntax.getEquationMarker())) {
                      // Starts with an equation sign. Evaluating.
                      final String equation = LmlUtilities.stripMarker(argument);
                      templateReader.append(newEquation().getResult(equation), equation + " equation");
                  } else if (Strings.startsWith(argument, syntax.getConditionMarker())) {
                      // Condition/ternary operator. Evaluating.
                      processConditionArgument(argument, argumentBuilder);
                  } else { // Regular argument. Looking for value mapped to the selected key.
                      templateReader.append(Nullables.toString(data.getArgument(argument)), argument + " argument");
                  }
                  return;
              }
              argumentBuilder.append(argumentCharacter);
          }
      }
docs: Found an argument opening sign. Have to find argument's name and replace it in the template.