old_contents: import test from 'tape';
  import string from './string';
  
  test(`\`string)\` throws \`TypeError\``, (assert) => {
    assert.throws(string.bind(void 0), TypeError,
      `Failed no argument.`);
    assert.end();
  });
  
  test(`\`stringundefined)\` throws \`TypeError\``, (assert) => {
    assert.throws(string.bind(void 0, void 0), TypeError,
      `Failed \`undefined\`.`);
    assert.end();
  });
  
  test(`\`stringnull)\` throws \`TypeError\``, (assert) => {
    assert.throws(string.bind(void 0, null), TypeError,
      `Failed \`null\`.`);
    assert.end();
  });
  
  test(`\`stringFunction)\` throws \`TypeError\``, (assert) => {
    assert.throws(string.bind(void 0, () => {}), TypeError,
      `Failed \`Function\`.`);
    assert.end();
  });
  
  test(`\`stringString)\` returns \`String\``, (assert) => {
    const value = `a string`;
    assert.equal(string(value), value,
      `Failed \`String\`.`);
    assert.end();
  });
  
  test(`\`stringObject)\` throws \`TypeError\``, (assert) => {
    assert.throws(string.bind(void 0, {}), TypeError,
      `Failed \`Object\`.`);
    assert.end();
  });
  
  test(`\`stringBoolean)\` throws \`TypeError\``, (assert) => {
    assert.throws(string.bind(void 0, true), TypeError,
      `Failed \`true\`.`);
    assert.throws(string.bind(void 0, false), TypeError,
      `Failed \`false\`.`);
    assert.end();
  });
  
  test(`\`stringNumber)\` throws \`TypeError\``, (assert) => {
    assert.throws(string.bind(void 0, 0), TypeError,
      `Failed \`0\`.`);
    assert.throws(string.bind(void 0, 1), TypeError,
      `Failed \`1\`.`);
    assert.throws(string.bind(void 0, 2), TypeError,
      `Failed \`2\`.`);
    assert.throws(string.bind(void 0, 123), TypeError,
      `Failed \`123\`.`);
    assert.throws(string.bind(void 0, -123), TypeError,
      `Failed \`-123\`.`);
    assert.throws(string.bind(void 0, 123.4567), TypeError,
      `Failed \`123.4567\`.`);
    assert.end();
  });
  
new_contents: import test from 'tape';
  import string from './string';
  
  test(`\`string()\` throws \`TypeError\``, (assert) => {
    assert.throws(string.bind(void 0), TypeError,
      `Failed no argument.`);
    assert.end();
  });
  
  test(`\`string(undefined)\` throws \`TypeError\``, (assert) => {
    assert.throws(string.bind(void 0, void 0), TypeError,
      `Failed \`undefined\`.`);
    assert.end();
  });
  
  test(`\`string(null)\` throws \`TypeError\``, (assert) => {
    assert.throws(string.bind(void 0, null), TypeError,
      `Failed \`null\`.`);
    assert.end();
  });
  
  test(`\`string(Function)\` throws \`TypeError\``, (assert) => {
    assert.throws(string.bind(void 0, () => {}), TypeError,
      `Failed \`Function\`.`);
    assert.end();
  });
  
  test(`\`string(String)\` returns \`String\``, (assert) => {
    const value = `a string`;
    assert.equal(string(value), value,
      `Failed \`String\`.`);
    assert.end();
  });
  
  test(`\`string(Object)\` throws \`TypeError\``, (assert) => {
    assert.throws(string.bind(void 0, {}), TypeError,
      `Failed \`Object\`.`);
    assert.end();
  });
  
  test(`\`string(Boolean)\` throws \`TypeError\``, (assert) => {
    assert.throws(string.bind(void 0, true), TypeError,
      `Failed \`true\`.`);
    assert.throws(string.bind(void 0, false), TypeError,
      `Failed \`false\`.`);
    assert.end();
  });
  
  test(`\`string(Number)\` throws \`TypeError\``, (assert) => {
    assert.throws(string.bind(void 0, 0), TypeError,
      `Failed \`0\`.`);
    assert.throws(string.bind(void 0, 1), TypeError,
      `Failed \`1\`.`);
    assert.throws(string.bind(void 0, 2), TypeError,
      `Failed \`2\`.`);
    assert.throws(string.bind(void 0, 123), TypeError,
      `Failed \`123\`.`);
    assert.throws(string.bind(void 0, -123), TypeError,
      `Failed \`-123\`.`);
    assert.throws(string.bind(void 0, 123.4567), TypeError,
      `Failed \`123.4567\`.`);
    assert.end();
  });
  
subject: fix typos in string messages.