add example

examples/opt_imports.rs

@@ -0,0 +1,28 @@
+extern crate pwasm_utils as utils;
+
+use std::env;
+
+fn main() {
+	let args = env::args().collect::<Vec<_>>();
+	if args.len() != 3 {
+		println!("Usage: {} input_file.wasm output_file.wasm", args[0]);
+		return;
+	}
+
+	// Loading module
+	let mut module = utils::Module::from_elements(
+		&parity_wasm::deserialize_file(&args[1]).expect("Module deserialization to succeed")
+	).expect("Failed to parse parity-wasm format");
+
+	let mut delete_types = Vec::new();
+	for type_ in module.types.iter() {
+		if type_.link_count() == 0 {
+			delete_types.push(type_.order().expect("type in list should have index"));
+		}
+	}
+	module.types.delete(&delete_types[..]);
+
+	parity_wasm::serialize_to_file(&args[2],
+		module.generate().expect("Failed to generate valid format")
+	).expect("Module serialization to succeed")
+}