tried to move source command into parser (still doesn't compile)

crates/nu-protocol/src/value/mod.rs

@@ -179,6 +179,7 @@ impl Value {
         }
     }
 
+    /// Follow a given column path into the value: for example accessing nth elements in a stream or list
     pub fn follow_cell_path(self, column_path: &[PathMember]) -> Result<Value, ShellError> {
         let mut current = self;
         for member in column_path {

crates/nu-protocol/src/value/range.rs

@@ -1,5 +1,6 @@
 use crate::{ast::RangeInclusion, *};
 
+/// A Range is an iterator over integers.
 #[derive(Debug, Clone, PartialEq)]
 pub struct Range {
     pub from: Value,