function isMatch(fp, pattern, opts) {
  if (typeof fp !== 'string') {
    throw new TypeError(msg('isMatch', 'filepath', 'a string'));
  }

  fp = utils.unixify(fp, opts);

  if (utils.typeOf(pattern) === 'object') {
    return matcher(fp, pattern);
  }

  return matcher(pattern, opts)(fp);
}
Returns true if the filepath contains the given
pattern. Can also return a function for matching.

```js
isMatch('foo.md', '*.md', {});
//=> true

isMatch('*.md', {})('foo.md')
//=> true
```
@param  {String} `fp`
@param  {String} `pattern`
@param  {Object} `opts`
@return {Boolean}