code: def h_v_t(header, key):
          
          if key not in header:
              key = key.title()
  
              if key not in header:
                  raise ValueError("Unexpected header in response, missing: " + key + " headers:\n" + str(header))
  
          return header[key]
docs: get header value with title
          try to get key from header and consider case sensitive
          e.g. header['x-log-abc'] or header['X-Log-Abc']
          :param header:
          :param key:
          :return: