title: How can you assert that all std::vector<std::string> are a given size in a one-liner?
body: <p>I have a method which accepts a std::vector of sha1 hashes as strings which must exactly 20 characters long. It would be great to assert in a one-liner that this precondition is respected.. </p>
  
  <pre><code>void MyClass::setSha1Sums(const std::vector&lt;std::string&gt;&amp; sha1Sums)
  {
    assert(magic_oneliner_which_verifies_that_all_strings_are_20_chars_long);
    sha1Sums_ = sha1Sums;
  }
  </code></pre>