code: public static <T extends AbstractHtml> Collection<T> findTagsAssignableToTag(
              final Class<T> tagClass, final AbstractHtml... fromTags)
              throws NullValueException, InvalidTagException {
          return findTagsAssignableToTag(false, tagClass, fromTags);
      }
docs: Finds and returns the all matching (including from nested tags) tags
  (which is assignable to the given tag class). <br>
  <br>
  
  <pre>
  <code>
  Html html = new Html(null) {{
  new Head(this) {{
  new TitleTag(this){{
  new NoTag(this, "some title");
  }};
  }};
  new Body(this, new Id("one")) {{
  new Div(this);
  new Div(this) {{
  new Div(this) {{
  new Div(this);
  }};
  }};
  new Div(this);
  }};
  }};
  
  Collection&lt;Head&gt; heads = TagRepository.findTagsAssignableToTag(Head.class, html);
  Collection&lt;Div&gt; divs = TagRepository.findTagsAssignableToTag(Div.class, html);
  
  System.out.println(heads.size());
  System.out.println(divs.size());
  
  //prints
  
  1
  5
  
  </code>
  </pre>
  
  @param tagClass
  the class of the tag.
  @param fromTags
  from which the findings to be done.
  @return the all matching tags which is assignable to the given tag class.
  @throws NullValueException
  if the {@code tagClass} or
  {@code fromTags} is null
  @throws InvalidTagException
  if the given tag class is NoTag.class
  @since 2.1.11
  @author WFF