code: def required_header(header):
      
      if header in IGNORE_HEADERS:
          return False
  
      if header.startswith('HTTP_') or header == 'CONTENT_TYPE':
          return True
  
      return False
docs: Function that verify if the header parameter is a essential header
  
      :param header:  A string represented a header
      :returns:       A boolean value that represent if the header is required