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diff --git a/third_party/rust/glean-core/src/traits/labeled.rs b/third_party/rust/glean-core/src/traits/labeled.rs
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+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at https://mozilla.org/MPL/2.0/.
+
+use crate::ErrorType;
+
+/// A description for the [`LabeledMetric`](crate::metrics::LabeledMetric) type.
+///
+/// When changing this trait, make sure all the operations are
+/// implemented in the related type in `../metrics/`.
+pub trait Labeled<T>
+where
+    T: Clone,
+{
+    /// Gets a specific metric for a given label.
+    ///
+    /// If a set of acceptable labels were specified in the `metrics.yaml` file,
+    /// and the given label is not in the set, it will be recorded under the special `OTHER_LABEL` label.
+    ///
+    /// If a set of acceptable labels was not specified in the `metrics.yaml` file,
+    /// only the first 16 unique labels will be used.
+    /// After that, any additional labels will be recorded under the special `OTHER_LABEL` label.
+    ///
+    /// Labels must be `snake_case` and less than 30 characters.
+    /// If an invalid label is used, the metric will be recorded in the special `OTHER_LABEL` label.
+    fn get(&self, label: &str) -> T;
+
+    /// **Exported for test purposes.**
+    ///
+    /// Gets the number of recorded errors for the given metric and error type.
+    ///
+    /// # Arguments
+    ///
+    /// * `error` - The type of error
+    ///
+    /// # Returns
+    ///
+    /// The number of errors reported.
+    fn test_get_num_recorded_errors(&self, error: ErrorType) -> i32;
+}