Used for complex manipulation, comparison, and access of array data. Some methods allow for
XPath-like data access, as follows:				
- `'/User/id'`: Similar to the classic {n}.User.id.

 - `'/User[2]/name'`: Selects the name of the second User.

 - `'/User[id>2]'`: Selects all Users with an id > 2.

 - `'/User[id>2][<5]'`: Selects all Users with an id > 2 but < 5.

 - `'/Post/Comment[author_name=John]/../name'`: Selects the name of
   all posts that have at least one comment written by John.

 - `'/Posts[name]'`: Selects all Posts that have a `'name'` key.

 - `'/Comment/.[1]'`: Selects the contents of the first comment.

 - `'/Comment/.[:last]'`: Selects the last comment.

 - `'/Comment/.[:first]'`: Selects the first comment.

 - `'/Comment[text=/lithium/i]`': Selects the all comments that have
   a text matching the regex `/lithium/i`.

 - `'/Comment/@*'`: Selects all key names of all comments.