prettyPrint method
Uses a rough approximation of reverse polish notation to render the parsed value of a FHIRPath in a more human readable way than verbosePrint, while still demonstrating how the expression was parsed and nested according to this package
Implementation
@override
String prettyPrint([int indent = 2]) => '${" " * indent}!='
'\n${" " * indent}${" " * indent}${before.prettyPrint(indent + 1)}'
'\n${" " * indent}${" " * indent}${after.prettyPrint(indent + 1)}';