code: protected Object getValue( QueryContext context,
                                 StaticOperand operand ) {
          if (operand instanceof Literal) {
              Literal literal = (Literal)operand;
              return literal.value();
          }
          BindVariableName variable = (BindVariableName)operand;
          return context.getVariables().get(variable.getBindVariableName());
      }
docs: Get the value associated with the static operand of the comparison. If the operand is a {@link BindVariableName variable
  name}, the variable value is returned.
  
  @param context the query context; may not be null
  @param operand the static operand; may not be null
  @return the value of the static operand