feat: implement comparison skeleton

This commit lays out the general idea of how the ComparisonData struct will work. It is expandable and I'm sure we will add more to it as time goes on.

src/utils/mod.rs

@@ -0,0 +1,23 @@
+use crate::common::{ExpandableInfo, ValueType};
+use std::ops::ControlFlow;
+
+pub fn get_number_list(student_info: &ExpandableInfo, member: &String) -> Result<Vec<f64>, String> {
+    match student_info.data.get(member) {
+        Some(ValueType::List(Some(list))) => {
+            let temp = list.iter().try_fold(vec![], |mut list_acc, item| {
+                if let ValueType::Number(Some(number)) = item {
+                    list_acc.push(number.parse::<f64>().unwrap());
+                    ControlFlow::Continue(list_acc)
+                } else {
+                    ControlFlow::Break(list_acc)
+                }
+            });
+
+            match temp {
+                ControlFlow::Continue(list) => Ok(list),
+                ControlFlow::Break(_) => return Err("List contains non-number values".to_owned()),
+            }
+        }
+        _ => return Err("Couldn't find the list".to_owned()),
+    }
+}