code: public Query andWhere(final Expression where) {
          if (this.where == null) {
              this.where = where;
          } else {
              this.where = and(this.where.enclose(), where.enclose());
          }
  
          return this;
      }
docs: The WHERE clause.
  <p/>
  If there is no where clause already defined, sets to the defined value.
  <p/>
  If there is already an expression for where defined, defines an <code>and</code> expression between old and new clauses.
  <p/>
  Example:
  <pre>
  query.where(eq(column("col1"),k(1)).andWhere(eq(column("col2"),k(2))
  
  will be translated to
  
  ("col1" = 1) AND ("col2" = 2)
  </pre>
  
  @param where The WHERE expression.
  @return This expression.