1. A computer-implemented method to access a data structure including a tree data structure in a computing environment, the method comprising: generating the data structure in the computing environment, the tree data structure having: a plurality of nodes, a node in the plurality of nodes embodying a plurality of fields, and at least one child link and at least one next link, the at least one child link and the at least one next link being used to link two or more nodes in the plurality of nodes; accessing contents of the data structure with an access command in the computing environment, the access command including: a reference to at least one node of the tree data structure, and a user-defined argument representing at least one of: a command to access contents of the data structure by following one or more child links in the tree data structure and one or more next links in the tree data structure, a command to access contents of the data structure by following one or more child links in the tree data structure and not following a next link in the tree data structure while the next link is present, or a command to access contents of the data structure by following one or more next links in the tree data structure and not following a child link in the tree data structure, the access command for accessing contents of the data structure based on the user-defined argument; and providing in the computing environment the contents of the data structure based on the access command.