title: 'Convert' TypeError checks to PyTypes @typechecked
body: <p>Goal: replace <code>TypeError</code> checks with <code>PyTypes</code>.</p>
  <p>I want to significantly shorten the beginning of many functions, by removing <code>TyperError</code> lines.</p>
  <p><a href="https://pypi.org/project/pytypes/" rel="nofollow noreferrer">PyTests</a> offers to do many TypeChecks under the hood.</p>
  <p>So far, I've imported, applied decorator and applied type hints:</p>
  <pre class="lang-py prettyprint-override"><code>from pytypes import typechecked
  
  @typechecked
  def _get_colours_for_n_lines(n_lines: int, input_colour_list: list,
                                      master_colour_list: list) -&gt; list:
      &quot;&quot;&quot;
      Checks if user-requested colours are available for n desired lines.
      &quot;&quot;&quot;
      if not isinstance(n_lines, int):
          raise TypeError('n_lines must be of type int')
      if not isinstance(input_colour_list, list):
          raise TypeError('Input colour list must be of type list')
      if not isinstance(master_colour_list, list):
          raise TypeError('Master colour list must be of type list')
      if not master_colour_list:
          raise TypeError('No master colour list to select from')
      
      # ...
  
      return input_colour_list
  </code></pre>
  <p>What else am I expected to do?</p>