code: def classify_field(value):
      
      if not (isinstance(value, six.string_types) and value):
          return
  
      schema = load_schema('elements/inspire_field')
      inspire_categories = schema['properties']['term']['enum']
  
      for inspire_category in inspire_categories:
          if value.upper() == inspire_category.upper():
              return inspire_category
  
      category = normalize_arxiv_category(value)
      return ARXIV_TO_INSPIRE_CATEGORY_MAPPING.get(category, 'Other')
docs: Normalize ``value`` to an Inspire category.
  
      Args:
          value(str): an Inspire category to properly case, or an arXiv category
              to translate to the corresponding Inspire category.
  
      Returns:
          str: ``None`` if ``value`` is not a non-empty string,
              otherwise the corresponding Inspire category.