Basic method setup and calling

Sources/HummingbirdMustache/Method.swift

@@ -0,0 +1,29 @@
+
+protocol HBMustacheBaseMethods {
+    func runMethod(_ name: String) -> Any?
+}
+protocol HBMustacheMethods {
+    typealias Method = (Self) -> Any
+    static var methods: [String: Method] { get set }
+}
+
+extension HBMustacheMethods {
+    static func addMethod(named name: String, method: @escaping Method) {
+        Self.methods[name] = method
+    }
+    func runMethod(_ name: String) -> Any? {
+        guard let method = Self.methods[name] else { return nil }
+        return method(self)
+    }
+}
+
+extension String: HBMustacheBaseMethods {
+    func runMethod(_ name: String) -> Any? {
+        switch name {
+        case "lowercased":
+            return self.lowercased()
+        default:
+            return nil
+        }
+    }
+}