Structural Expression Functions
- Depth — get maximum number of indices to specify any part
- FreeQ — test whether an expression is free of subexpressions matching a pattern
- Level — get parts specified by a given number of indices
- MapApply — apply a function to a list, at the top level
- Null — implicit result for expressions that do not yield a result
- SortBy — sort by the values of a function applied to elements