code: @SuppressWarnings("unchecked")
      public <T> T getValue(final String variableName) {
          final Variable variable = getVariable(variableName);
          return (variable == null) ? null : (T) variable.getValue();
      }
docs: Load the current value of a given variable.
  @param variableName The name of the variable we are looking up.
  @param <T> The data type of the exported variable.
  @return Null if the variable was not found. The value otherwise.