move this function to lib so we can use it elsewhere

src/lib.rs

@@ -133,6 +133,18 @@ fn segments_from_string(string: String) -> Vec<String> {
     output
 }
 
+// for some reason the sprites with numeric IDs go first,
+// then SPR A (avatar), then all the non-numeric IDs
+fn is_string_numeric(str: String) -> bool {
+    for c in str.chars() {
+        if !c.is_numeric() {
+            return false;
+        }
+    }
+
+    return true;
+}
+
 #[cfg(test)]
 mod test {
     use crate::{from_base36, ToBase36, optional_data_line, mock, segments_from_string};