diff --git a/examples/word-count-cls/.gitignore b/examples/word-count-cls/.gitignore
new file mode 100644
index 00000000..db8bc200
--- /dev/null
+++ b/examples/word-count-cls/.gitignore
@@ -0,0 +1,67 @@
+target/
+**/*.rs.bk
+Cargo.lock
+
+# Byte-compiled / optimized / DLL files
+__pycache__/
+*.py[cod]
+
+# C extensions
+*.so
+
+# Distribution / packaging
+.Python
+env/
+build/
+develop-eggs/
+dist/
+downloads/
+eggs/
+.eggs/
+lib/
+lib64/
+parts/
+sdist/
+var/
+bin/
+local/
+include/
+man/
+*.egg-info/
+.installed.cfg
+*.egg
+.ropeproject/
+
+# PyInstaller
+#  Usually these files are written by a python script from a template
+#  before PyInstaller builds the exe, so as to inject date/other infos into it.
+*.manifest
+*.spec
+
+# Installer logs
+pip-log.txt
+pip-delete-this-directory.txt
+pip-selfcheck.json
+
+# Unit test / coverage reports
+htmlcov/
+.tox/
+.coverage
+.coverage.*
+.cache
+nosetests.xml
+coverage.xml
+*,cover
+
+# Translations
+*.mo
+*.pot
+
+# Django stuff:
+*.log
+
+# Sphinx documentation
+docs/_build/
+
+# PyBuilder
+target/
diff --git a/examples/word-count-cls/Cargo.toml b/examples/word-count-cls/Cargo.toml
new file mode 100644
index 00000000..43fbd3ff
--- /dev/null
+++ b/examples/word-count-cls/Cargo.toml
@@ -0,0 +1,14 @@
+[package]
+authors = ["Messense Lv <messense@icloud.com>"]
+name = "word-count"
+version = "0.1.0"
+
+[dependencies]
+rayon = "0.8"
+
+[dependencies.pyo3]
+path = "../../"
+
+[lib]
+name = "word_count"
+crate-type = ["cdylib"]
diff --git a/examples/word-count-cls/README.md b/examples/word-count-cls/README.md
new file mode 100644
index 00000000..0a38437f
--- /dev/null
+++ b/examples/word-count-cls/README.md
@@ -0,0 +1,15 @@
+# word-count
+
+## Build
+
+```bash
+python setup.py install
+```
+
+## Usage
+
+```python
+from word_count_cls import WordCounter
+
+WordCounter().search('path/to/file', 'word')
+```
diff --git a/examples/word-count-cls/setup.py b/examples/word-count-cls/setup.py
new file mode 100644
index 00000000..306fe0cc
--- /dev/null
+++ b/examples/word-count-cls/setup.py
@@ -0,0 +1,54 @@
+import sys
+
+from setuptools import setup
+from setuptools.command.test import test as TestCommand
+
+try:
+    from setuptools_rust import RustExtension
+except ImportError:
+    import subprocess
+    errno = subprocess.call([sys.executable, '-m', 'pip', 'install', 'setuptools-rust'])
+    if errno:
+        print("Please install setuptools-rust package")
+        raise SystemExit(errno)
+    else:
+        from setuptools_rust import RustExtension
+
+
+class PyTest(TestCommand):
+    user_options = []
+
+    def run(self):
+        self.run_command("test_rust")
+
+        import subprocess
+        import sys
+        errno = subprocess.call([sys.executable, '-m', 'pytest', 'tests'])
+        raise SystemExit(errno)
+
+
+setup_requires = ['setuptools-rust>=0.6.1']
+install_requires = []
+tests_require = install_requires + ['pytest', 'pytest-benchmark']
+
+setup(
+    name='word-count-cls',
+    version='0.1.0',
+    classifiers=[
+        'License :: OSI Approved :: MIT License',
+        'Development Status :: 3 - Alpha',
+        'Intended Audience :: Developers',
+        'Programming Language :: Python',
+        'Programming Language :: Rust',
+        'Operating System :: POSIX',
+        'Operating System :: MacOS :: MacOS X',
+    ],
+    packages=['word_count_cls'],
+    rust_extensions=[RustExtension('word_count_cls._word_count', 'Cargo.toml')],
+    install_requires=install_requires,
+    tests_require=tests_require,
+    setup_requires=setup_requires,
+    include_package_data=True,
+    zip_safe=False,
+    cmdclass=dict(test=PyTest)
+)
diff --git a/examples/word-count-cls/src/lib.rs b/examples/word-count-cls/src/lib.rs
new file mode 100644
index 00000000..5dbe44df
--- /dev/null
+++ b/examples/word-count-cls/src/lib.rs
@@ -0,0 +1,89 @@
+// Source adopted from
+// https://github.com/tildeio/helix-website/blob/master/crates/word_count/src/lib.rs
+#![feature(proc_macro, specialization, const_fn)]
+extern crate pyo3;
+extern crate rayon;
+
+use std::fs::File;
+use std::io::prelude::*;
+
+use rayon::prelude::*;
+use pyo3::*;
+
+#[py::class]
+struct Words {
+    path: String,
+    token: PyToken,
+}
+
+#[py::methods]
+impl Words {
+
+    #[new]
+    fn __new__(_cls: &PyType, py: Python, path: String) -> PyResult<PyObject> {
+        Ok(py.init(|t| Words {path: path, token: t})?.into())
+    }
+
+    fn search(&self, py: Python, search: String) -> PyResult<i32> {
+        let mut file = File::open(self.path.as_str())?;
+        let mut contents = String::new();
+        file.read_to_string(&mut contents)?;
+
+        let count = py.allow_threads(move || wc_parallel(&contents, &search));
+        Ok(count)
+    }
+
+    fn search_sequential(&self, search: String) -> PyResult<i32> {
+        let mut file = File::open(self.path.as_str())?;
+        let mut contents = String::new();
+        file.read_to_string(&mut contents)?;
+        Ok(wc_sequential(&contents, &search))
+    }
+}
+
+
+fn matches(word: &str, search: &str) -> bool {
+    let mut search = search.chars();
+    for ch in word.chars().skip_while(|ch| !ch.is_alphabetic()) {
+        match search.next() {
+            None => { return !ch.is_alphabetic(); }
+            Some(expect) => {
+                if ch.to_lowercase().next() != Some(expect) {
+                    return false;
+                }
+            }
+        }
+    }
+    return search.next().is_none();
+}
+
+fn wc_line(line: &str, search: &str) -> i32 {
+    let mut total = 0;
+    for word in line.split(' ') {
+        if matches(word, search) {
+            total += 1;
+        }
+    }
+    total
+}
+
+fn wc_sequential(lines: &str, search: &str) -> i32 {
+    lines.lines()
+         .map(|line| wc_line(line, search))
+         .fold(0, |sum, line| sum + line)
+}
+
+fn wc_parallel(lines: &str, search: &str) -> i32 {
+    lines.par_lines()
+         .map(|line| wc_line(line, search))
+         .sum()
+}
+
+
+
+#[py::modinit(_word_count)]
+fn init_mod(_py: Python, m: &PyModule) -> PyResult<()> {
+    m.add_class::<Words>()?;
+
+    Ok(())
+}
diff --git a/examples/word-count-cls/tests/test_word_count.py b/examples/word-count-cls/tests/test_word_count.py
new file mode 100644
index 00000000..e582d2dd
--- /dev/null
+++ b/examples/word-count-cls/tests/test_word_count.py
@@ -0,0 +1,55 @@
+# -*- coding: utf-8 -*-
+from __future__ import absolute_import
+
+import os
+
+import pytest
+
+import word_count_cls
+
+current_dir = os.path.abspath(os.path.dirname(__file__))
+path = os.path.join(current_dir, 'zen-of-python.txt')
+
+
+@pytest.fixture(scope='session', autouse=True)
+def textfile():
+    text = '''The Zen of Python, by Tim Peters
+
+Beautiful is better than ugly.
+Explicit is better than implicit.
+Simple is better than complex.
+Complex is better than complicated.
+Flat is better than nested.
+Sparse is better than dense.
+Readability counts.
+Special cases aren't special enough to break the rules.
+Although practicality beats purity.
+Errors should never pass silently.
+Unless explicitly silenced.
+In the face of ambiguity, refuse the temptation to guess.
+There should be one-- and preferably only one --obvious way to do it.
+Although that way may not be obvious at first unless you're Dutch.
+Now is better than never.
+Although never is often better than *right* now.
+If the implementation is hard to explain, it's a bad idea.
+If the implementation is easy to explain, it may be a good idea.
+Namespaces are one honking great idea -- let's do more of those!\n''' * 1000
+    with open(path, 'w') as f:
+        f.write(text)
+    yield
+    os.remove(path)
+
+
+def test_word_count_rust_parallel(benchmark):
+    count = benchmark(word_count_cls.Words(path).search, 'is')
+    assert count == 10000
+
+
+def test_word_count_rust_sequential(benchmark):
+    count = benchmark(word_count_cls.Words(path).search_sequential, 'is')
+    assert count == 10000
+
+
+def test_word_count_python_sequential(benchmark):
+    count = benchmark(word_count_cls.search_py, path, 'is')
+    assert count == 10000
diff --git a/examples/word-count-cls/word_count_cls/__init__.py b/examples/word-count-cls/word_count_cls/__init__.py
new file mode 100644
index 00000000..eab0efd4
--- /dev/null
+++ b/examples/word-count-cls/word_count_cls/__init__.py
@@ -0,0 +1,17 @@
+# -*- coding: utf-8 -*-
+from __future__ import absolute_import
+
+from ._word_count import Words
+
+__all__ = ['Words', 'search_py']
+
+
+def search_py(path, needle):
+    total = 0
+    with open(path, 'r') as f:
+        for line in f:
+            words = line.split(' ')
+            for word in words:
+                if word == needle:
+                    total += 1
+    return total